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Venturi Skimmer

Contents:

  1. RE: (m) DIY venturi skimmer request, repeated
    by CHUCK-at-PIERRE.MIT.EDU (Chuck Parsons) (Wed, 25 Mar 1992)
  2. Protein skimmer design & Secrets of the siphon break (long)
    by fernando-at-aplcomm.jhuapl.edu (Fernando Pineda) (Mon, 2 Nov 1992)
  3. Skimmer design & Siphon break (uncorrupted I hope)
    by fernando-at-aplcomm.jhuapl.edu (Fernando Pineda) (2 Nov 92)
  4. [M] Home-brew Protein Skimmer Possible?
    by davep-at-paladin.corp.sgi.com (David Packer) (3 Feb 1993)
  5. [M] Home-brew Protein Skimmer Possible?
    by dbs-at-hprnd.rose.hp.com (Dave Sheehy) (3 Feb 93)
  6. RE: (m) DIY venturi skimmer request, repeated
    by IN%"CHUCK-at-PIERRE.MIT.EDU" 25-MAR-1992 07:06:14.61 ()
  7. [M] Home-brew Protein Skimmer Possible?
    by davep-at-paladin.corp.sgi.com (David Packer) (3 Feb 1993)
  8. protein skimmer design
    by hagemepp-at-esu.edu (Pete Hagemeyer) (15 Jun 1994)
  9. [M] Home-brew Protein Skimmer Possible?
    by HCM100-at-psuvm.psu.edu (Hans C. Masing) ()
  10. Construction of a Counter Current Foam Fractionator (Long)
    by jto-at-dynsim1.litwin.com ()
  11. RE: (m) DIY venturi skimmer request, repeated
    by IN%"CHUCK-at-PIERRE.MIT.EDU" 25-MAR-1992 07:06:14.61 ()
  12. Protein Skimmer Design & the secrets of the siphon break
    by tj-at-kona.cs.ucla.edu (Tom Johnson) (3 Nov 92)
  13. (M) UV Sterilizer & Protein skimmer
    by jmk-at-cbvox.att.com (Joseph M Knapp) (Wed, 15 Jan 92)
  14. (M) How to build a protein skimmer
    by rbraun-at-spdcc.COM (Rich Braun) (28 Jun 91)
  15. homebrew skimmers
    by richb-at-kronos.com (Rich Braun) (1 Dec 91)
  16. (m) Venturi Skimmer valves
    by perry-at-cbmvax.commodore.com (Perry Weinthal) (26 Mar 92)
  17. Skimmy Information
    by ahughes-at-arch386.hyperdesk.com (Arch Hughes) (22 Jun 92)
  18. DIY Venturi skimmer - anyone done this ?
    by kncarp-at-nicsn1.monsanto.com (Kevin N. Carpenter) (Thu, 18 Feb 1993)
  19. home brew skimer plan
    by rivan-at-bcarh970.bnr.ca (Robert Ivan) (17 Jan 1994)
  20. home brew skimer plan
    by rivan-at-bcarh970.bnr.ca (Robert Ivan) (17 Jan 1994)

RE: (m) DIY venturi skimmer request, repeated

by CHUCK-at-PIERRE.MIT.EDU (Chuck Parsons)
Date: Wed, 25 Mar 1992

In article <1992Mar24.210935.1-at-pomona.claremont.edu>, you write...
> 
>Hi all again-
> 
>      Sorry if this bothers you too much, but I thought I would try one last
>time- Anyone have the DIY Venturi skimmer plans that were posted (last year, I
>think)? Me and a couple other people who emailed me would appreciate them if
>anyone has them.
> 
>Sorry, and thanks.
> 
  I have built two venturi skimmers. I have to be brief I'm very
busy this week.

  for both I used powerheads. 

  For the first one I used a visijet powerhead. It was a 
in tank unit. I took a 20"x3" plexi tube open at the 
bottom, and cut a slot in the
top to accept the visijet input. The visijet was at the top
of the water level. The visijet venturi worked great, the bubles
would go almost to the bottom of the tube before turning around
and coming back up. The top of the tube served to collect the
foam. It had a small angled ledge with a drain to catch the foam
and a lid. Worked well but was in the tank.

 For the second one I used a 201 powerhead. The Venturi feature
sucked. So I drilled a small hole in the botom of the powerhead to 
allow me to put an air tube at the center of the impeller. This
makes a good venturi. I used a  24"x4" tube closed at the
bottom and added PVC elbows for an inlet and an outlet. Since
it sits in my sump it doesn't have to be perfectly water tight.
It would be watertight but I made the bottom slip on and off
for easy cleaning. A 4"x18"x1/8" plastic insert inside the tube
divdes the bottom 3/4 of tube in half. Aireated water comes
in one side up over the divider and down the otherside. You 
need to be able to adjust the flow on both the input and output.
The powerhead controls can be used for the input but a ballvalve
is nicer. Adjust the output so that the water is 1-2" higher
than the divider. The top section of tube can be cut off to
make the foam collector. Cut a 1" piece of tube and remove
2*pi*tube_thickness on one side making a braclet. If you push
the cut together the cut piece will just fit inside the uncut
tube pieces. Glue it in the top piece and now your foam collector is
removable. Add a ledge in the bottom to catch the foam.


Regards, Chuck-at-pierre.mit.edu

P.S. To drill holes for the PVC fittings you need to tightly
wedge a piece of wood in the tube so you can drill in to the wood.
Other wise you won't ge a round hole. 




Protein skimmer design & Secrets of the siphon break (long)

by fernando-at-aplcomm.jhuapl.edu (Fernando Pineda)
Date: Mon, 2 Nov 1992

Cheap protein skimmer design & Secrets of the siphon break

SUMMARY ------------------------------------------------------------------

About 1 1/2 years ago I went through the exercise of building my own 
countercurrent skimmer(s) out of PVC and CPVC pipe. I used a photograph from 
FAMA as a "blue print."  I could have bought a skimmer for what I spent in
R&D, 
but I now know how to make cheap and effective skimmers. The price is more or 
less independent of the height. I also understand why a siphon break is 
important for counter current skimmers (ItÕs not what you think!). 
Surprisingly, it has more to do with making the skimmer controllable than in 
preventing floods. Here are my notes. The first section is the design, the 
second section is an analysis of how a siphon break affects the stability of 
the skimmer. If you donÕt like math, the bottom line is that without the
siphon 
break the output valve becomes very sensitive. The sensitivity increases 
roughly in proportion to the square of the height of the skimmer.  Without a 
siphon break, a 4Õ skimmer is very difficult (if not impossible) to adjust.  
ItÕs not hard to see why a lot of people complain about not being able to 
adjust their skimmers! Put in a siphon break and your problems will go away!

Let me know if you build one. 

BUILDING A PVC SKIMMER -------------------------------------------------
PVC is much cheaper than acrylic and available everywhere.  I have never found
any need to look inside the skimmer, in fact I suspect a PVC skimmer may be 
cleaner than an acrylic one since the lack of light prevents algea from
growing 
inside the skimmer. Of the three skimmers I built, one I threw out, one I'm 
using (18" tall) and the third (4' tall) is waiting for a bigger tank. With no
mistakes each skimmer can be made for about $30-$50 depending on how much you 
spend on valves and on whether you have to buy PVC glue, silicone, rubber 
gaskets, etc. Also IÕm not counting things like drill bits, and hacksaws.  The
basic design criteria for a homemade skimmer are:

1) The skimmer should be cheap <$50
2) Requires just a hacksaw, a power drill and a knife for construction
3) Parts are available at any hardware store
4) Easy to operate
5) Easy to keep clean

PARTS (plus lots of little things I probably forgot )----------
    4" PVC 
        1 pipe (comes in 8' sections, but a remnant is just a few dollars)
        3 ÒclosetÓ flanges (~$4 each?)
        O-ring that can seal two flanges (or make you own from rubber sheet)
   3/4" CPVC 
       1 tube (come in 8' sections but it's just cents per foot )
       various elbows (~$0.50 ? each)
       2 CPVC adapters that go from 3/4" tubing to to male threads (~$.50
each)
       2 CPVC ball values (<$5.00 each)
   3   2"-long 1/4" nylon bolts with wing nuts
   6Óx 6Ó Rubber sheet or O-ring
   1 rigid airline tubing ~2' length
   1 soft airline tubing ~1' length
   1 coupler for airline tubing
   2 limewood airstones + check valve


CONSTRUCTION -----------
First, assemble the skimmer, but don't glue anything. After you are sure 
everything fits, then glue it together. Do not glue the skimmer cup assembly
to 
the body of the skimmer. You may have to seal the inflow/outflow connections
on 
the INSIDE of the skimmer with silicone sealant to stop leaks.

1) BODY OF SKIMMER
Cut the 4" PVC pipe to the height of the skimmer (say, 18"). Attach the
flanges 
to both ends of the pipe. Stand the skimmer up on one flange and punch out the
knockout of the top flange (Closet flanges have a knockout that is not removed
until plumbers can pressure test their connections). Now the skimmer is sealed
at the bottom and has a 4" wide  hole at the top. Just under the flange (not 
too close) drill two holes to accommodate PVC tubing. Make sure your holes are
ROUND otherwise they will leak. Holes should be at least 2" apart horizontally
AND 2" apart vertically. The bottom hole is the water input. The top hole is 
the water output. 
b
lems will go away!
Penetrate output hole with 4" piece of P
VC tube and extend ~1/2" inside skimmer. Run an elbow and a 16" length of PVC
t
ube from the output hole to the bottom of the skimmer (on the inside!). Make s
ure elbow is firmly attached to 16" and 4" pieces of PVC. Make sure elbow is 
flush against the inside of the skimmer. With this arrangement water is fed in
 at the top of the water column and removed at th
e
 bottom ("counter current" ). 

Penetrate input hole with 1 1/2" length of P
VC. Fit flush against inside of skimmer ...or... extend tubing 1/2 inch int
o skimmer and attach elbow that directs water current so
 
it swirls around the skimmer. 

2) S
IPHON BREAK & EXTERNAL PLUMBING
Connect elbow to outside of 4" penetrating outpu
t tube and point it downwards. 
Drill 1/8" hole through top of elbow or thr
ough top of penetrating tubing. Attach at least 6" of soft airline tubing t
o 1/8" hole with airline tubing coupler. Tubing must be rigid enough 
to stick straight up by itself.
Connect valves to input and output lines. You m
ight need t
h
e tubing-to-thr
eads adaptors. 

3) SKIMMER CUP
Take the remaining flange. Do not punch out th
e 4" seal, instead drill a 3/4" hole in the center. Lay the flange
"back-to-back
" on the open flange already on the skimmer. Attach a 3/4" coupler to the hole
 and insert a 4" length of 3/4" tubing into the coupler. Cut 6" high piece of
4"
-PVC pipe and connect it to the flange. For lack of a better name let's call
th
is the crud-output tube. Notice how any liquid that comes out of the 4" tube
wi
ll get caught in the cup formed by the flange and the 6" section of 4"-PVC
pipe.
 Drill a drain hole in the SIDE of the cup near the bottom. Use whatever size
t
o
wn from rubber sheet)
 €
Connect the skimmer cup to the skimmer by boltin
g the flanges together with the nylon bolts (Do not glue!). You will ne
ed either an O-ring to seal the connection. Buy one or make your own from e
ither a sheet of rubber or from silicone sealant. Tape the airline coming from
the siphon brake to the skimmer cup so that the opening of the airlin
e
 is abo
ve the top of the cup. 

4) AIR
OK,  I forgot to explain how to put in the rig
id air line. Run it through the top of the crud-output tube to the bottom of
the
 skimmer.  Attach your limewood airstones and bolt on the skimmer cup assembl
y. Or, if you are feeling fancy you can drill a hole through the side of the
ski
mmer, so you donÕt have to fool with the air line when you clean the skimmer
cu
p. Put
 
a check valve in the air
 
line.

OPERATION -------------

To start the skimmer open the output valve c
ompletely. And adjust the input valve until you get the desired throughput.
Next
, slowly close the output valve until the water level in the skimmer reache
s the middle of the crud-output tube. Make these adjustments slowly because t
he water level will continue to change for 
r a while. You may want to make further adjustments on the output val
v
e to control the water level. 

I rarely have to adjust my skimmer. Also it'
s not too difficult to make the initial adjustments.  Major floods can't
happen 
if your skimmer-cup-drain feeds into a big enough bucket. Cleaning the skimmer
 can be done easily by brushing out the crud-tube or for more serious
servicing
 you can u
n
bolt the skimmer cup assembly.

SECRETS OF THE SIPHON BREAK ------------
-------------------------------
HereÕs a quantitative analysis to understand the
 importance of the siphon break for controlling the skimmer.  Let Òf_outÓ be
th
e rate of water outflow and let Òf_inÓ be the rate of water inflow.  The water
l
evel 
i
n the skimmer is constant when

(1)
 
                 f_in = f_out.

Now, letÕs build a simple model for the o
utput valve: Let the water flow through a valve be equal to the pressure, ÒpÓ,
(
AT THE VALVE!) and to the cross
 
section of the valve, ÒAÓ. So 

(
2)                f_out = p*A,

Let the cross-section A of the valve be pr
oportional to ÒthetaÓ the angle through which you have turned the handle of
the 
val
a
nt for the drain.  
P",‚
(3) 
 
            f_out = K*p *theta

Where K is 
a
 constant of proportionality. 

Now, let ÒhÓ be the level of the water in the sk
immer. If you fill the skimmer, open the output valve and let the water drain
 out, the water level will fall until the pressure at the valve is zero.  Let
Ò
h_oÓ be the corresponding water level.  So for any height of water h,
 
 the pressure at the valve is 

(
4
)              p =C*(h - h_0).

Where C is a constant of proportionality.  Fina
lly, upon substituting (4) i
n
to (3) and using (1) we obtain

(5)              f_in =
 
K*C
*(h - h_0) *theta          

or
      
                          f_in 
(6)        
     theta =  _________________
          
 
                K*C*(h - h_0) 

This equation gives the valve angle in term
s of the inflow and the desired water height, h. Now, letÕs ask the question: 
How much do we have to turn the valve to get a small change ÒdhÓ in the heigh
t of the water column? A 
s
imple differentiation produces

               
                           f_in
(7)            d( theta) 
=   _   ____________________ dh
                    
 
               K*C*(h - h_0)^2

Where Ò^2Ó  means the quantity squared. From 
this expression we can conclude the following. The higher the water column is
 above h_o, the LESS one has to turn the valve to get a given change, dh, in
the
 water column.  In other words, if (h-h_o) is large, a small change in the pos
ition of the valve results in a big change in the height of of the column.Now,
letÕs plug in some real numbers for the counter c

ItÕs not hard to see why a lot of people complain about not being able to 
adjust their skimmers! Put in those antisiphon holes and your problems will go
away!

Fernando Pineda (fernando-at-aplcomm.jhuapl.edu)

Skimmer design & Siphon break (uncorrupted I hope)

by fernando-at-aplcomm.jhuapl.edu (Fernando Pineda)
Date: 2 Nov 92

The last post was hopelessly corrupted. I'n not sure what happened. Here it is
again.

Cheap protein skimmer design & Secrets of the siphon break (long)


SUMMARY ------------------------------------------------------------------

About 1 1/2 years ago I went through the exercise of building my own 
countercurrent skimmer(s) out of PVC and CPVC pipe. I used a photograph from 
FAMA as a "blue print."  I could have bought a skimmer for what I spent in 
R&D, but I now know how to make cheap and effective skimmer. The price is more
or less independent of the height. I also understand why a siphon break is 
important for counter current skimmers (ItUs not what you think!). 
Surprisingly, it has more to do with making the skimmer controllable than in 
preventing floods. Here are my notes. The first section is the design, the 
second section is an analysis of how a siphon break affects the stability of 
the skimmer. If you donUt like math, the bottom line is that without the 
siphon break the output valve becomes very sensitive. The sensitivity 
increases roughly in proportion to the square of the height of the skimmer.  
Without a siphon break, a 4U skimmer is very difficult (if not impossible) to 
adjust.  ItUs not hard to see why a lot of people complain about not being 
able to adjust their skimmers! Put in a siphon break and your problems will go
away!

BUILDING A PVC SKIMMER -------------------------------------------------

PVC is much cheaper than acrylic and available everywhere.  I have never found
any need to look inside the skimmer, in fact I suspect a PVC skimmer may be 
cleaner than an acrylic one since the lack of light prevents algea from 
growing inside the skimmer. Of the three skimmers I built, one I threw out, 
one I'm using (18" tall) and the third (4' tall) is waiting for a bigger tank.
With no mistakes each skimmer can be made for about $30-$50 depending on how 
much you spend on valves and on whether you have to buy PVC glue, silicone, 
rubber gaskets, etc. Also IUm not counting things like drill bits, and 
hacksaws.  The basic design criteria for a homemade skimmer are:

1) The skimmer should be cheap <$50
2) Requires just a hacksaw, a power drill and a knife for construction
3) Parts are available at any hardware store
4) Easy to operate
5) Easy to keep clean


PARTS (plus lots of little things I probably forgot )----------

    4" PVC 
        1 pipe (comes in 8' sections, but a remnant is just a few dollars)
        3 RclosetS flanges (~$4 each?)
   3/4" CPVC 
       1 tube (come in 8' sections but it's just cents per foot )
       various elbows (~$0.50 ? each)
       2 CPVC adapters that go from 3/4" tubing to male threads(~$.50 each)

       2 CPVC ball values (<$5.00 each)
   3   2"-long 1/4" nylon bolts with wing nuts

   6Sx 6S Rubber sheet or O-ring
   1 rigid airline tubing ~2' length
   1 soft airline tubing ~1' length
   1 coupler for airline tubing
   2 limewood airstones + check valve

CONSTRUCTION -----------

First, assemble the skimmer, but don't glue anything. After you are sure 
everything fits, then glue it together. Do not glue the skimmer cup assembly 
to the body of the skimmer. You may have to seal the inflow/outflow 
connections on the INSIDE of the skimmer with silicone sealant to stop leaks.

1) BODY OF SKIMMER

Cut the 4" PVC pipe to the height of the skimmer (say, 18"). Attach the 
flanges to both ends of the pipe. Stand the skimmer up on one flange and punch
out the knockout of the top flange (Closet flanges have a knockout that is not
removed until plumbers can pressure test their connections). Now the skimmer 
is 4U =48S high and we want to keep the water level at 48S. Assume that 
without the antisiphon,(h-h_o) = 45S and with the antisiphon,  (h-h_o) = 4S, 
then the output valve is approximately (20S/4S)^2 = 126 TIME MORE SENSITIVE 
than it is with the antisiphon valve. 

ItUs not hard to see why a lot of people complain about not being able to 
adjust their skimmers! Put in those antisiphon holes and your problems will go
away!

Fernando Pineda (fernando-at-aplcomm.jhuapl.edu)

[M] Home-brew Protein Skimmer Possible?

by davep-at-paladin.corp.sgi.com (David Packer)
Date: 3 Feb 1993


I'm currently building my own skimmer.  What I did was go to a place
that's local that deals with plastics.

This is what I bought and the approximate costs:

1 -  24" long 3" diameter clear acrylic tube   $10.50 // main tube
1 -   4" long 2" diameter clear acrylic tube     3.00 // cup to tube
1 -   3" long 4" diameter clear acrylic tube     4.00 // for cup
2 -   4" diameter plates + 2" dia cut in one     2.50 // for cup
1 -   3" diameter -> 2" diameter bushing         3.50 
2 - 3/4" 4" long tubes - for in/out fittings     2.50 


My tank is a 55 gal. I put the skimmer in the sump I use an
Aqua-Clear 802 to drive the skimmer. On the output side I have
a valve, that is very acurate and I use the valve to adjust the
level of the water in the column. I just finished it and it seems
to work fairly well at a fraction of the cost of a comparable skimmer.

Dave

[M] Home-brew Protein Skimmer Possible?

by dbs-at-hprnd.rose.hp.com (Dave Sheehy)
Date: 3 Feb 93

Ok, I got enough requests for my collection of skimmer plans to justify
reposting them. Here goes:

- --------------------------------------------------------------------------

In article <4104-at-bnr-rsc.UUCP>, dbailey-at-bcarh184.bnr.ca (Doug Bailey) says:
>Has anyone made a protein skimmer?  Could you share the plans with us?

Just so happens that I built a very efficient reverse-flow protien skimmer for
my Marine tank for under $30, uncluding the pump.

I used PVC and CPVC pipe and fittings, available REEALLLLY cheap from your
local builders supply warehouse.

A basic supply list is included below.  Prices are approximated.

      4' length of 2" PVC pipe        $3.00
      End Cap for 2" pipe             $1.25
      Screw-end adapter for 2" pipe   $1.25
      2" to 3" adapter                $1.50
      2" to 1" adapter                $ .95
      10' 1/2" CPVC pipe              $2.50
      5 - 1/2" elbows    $.12 ea      $ .60
      1 - 1/2" T-connector            $ .25
      2 - 1/2" EndCaps   $.10 ea      $ .20
      4' 3/4" vinyl hose $.60 ft      $2.40
      2 Glass Airstone                $3.00
        (Yes, Glass.  I'll explain)
      Powerhead                       ----- (Already on aquarium)
      PVC Cement (for drinking water) $4.50
      Aquarium Sealant                $3.99
      1 3/4" hose clamp (optional)    $ .27

      Tools that would be helpfull: Pipe Cutter, Electric Drill, 3/4" bit,
                                    1/8" bit, Razor blade, hammer


      I drilled two 3/4" holes in the pipe, one on one side about 8" from the
top of the tube, the other on the other side about 2" from the bottom of the
tube.  I then sealed up the bottom of the tube with the end-cap and cement.

      I cut 1" lengths of vinyl tubing and 1 1/2" lengths of 1/2" cpvc pipe.
Put the tubing in the holes in the pipe and hammer the pieces of cpvc in the
tubing, creating a very tight seal.  Make sure that enough cpvc is sticking
out of the tubing to attach elbow joints to them.

      The top hole is the water in, and the bottom is the exit.  Put an elbow
facing upwards on the bottom hole.  Cut a length of cpvc long enough to reach
to about 3" below the top of the tube and fix an elbow joint facing towards
the tank.  You can get as fancy as you like with the water return.  I made
a simple T-shaped sprinkler, using the T-joint, endcaps and 5" pieces of CPVC.
I drilled 1/8" holes along the bottom and the water sprinkled very nicely into
the tank.  IT IS VERY IMPORTANT THAT THE RETURN TUBE BE ABOUT 3" BELOW THE TOP
OF THE TUBE.  OTHERWISE YOU ARE GOING TO GET VERY WET!!  The return flow
relies
on the pressure and weight of the water and the differences on the tube
diameter.  If the return tube is too high, the water will pour out of the top
of the skimmer, too low and you will never be able to collect foam.

     The foam collection cup is very simple.  Put the 1" to 2" adapter inside
the 2" to 3" adapter and glue it in place.  Also. place the 2" screw adapter
on the top of the large tube.  The foam collector should fit right over the
screw adapter, but be removable for emptying.  The collector will hold about 1
cup of foam.

      I put a bead of aquarium sealant all around the joints and inside the
foam collector.

      Use the tubing to connect the intake to your power head or other water
pump.  Be careful when first turning it on and make sure that the water level
in the skimmer remains about 2" below the top of the tube.  If it is too low,
lengthen the exit tube.  Too high, shorten it.

      Good luck, and if there are any questions, I'll try to answer them.

      Fishies rule!
      Hans

- --------------------------------------------------------------------------

Hiya everyone.

      One question that I was asked a number of times was the difference
between PVC and CPVC.  PVC is Poly-Vinyl-Chloride (I think) and is used
for plumbing and drainage.  It is white and pretty heavy duty stuff.  CPVC is
Chloro-Poly-Vinyl-Chloride (I think again) and is yellowish in color.  It is
used for drinking water supplies mostly.  Both are safe for aquarium use.  The
difference lies in the flexibility and cost, but mostly in available sizes.

      I neglected to tell why I use glass airstone vice wooden.  I tried the
wooden airstones and found that I got TOO MUCH (!?) foam.  The foam was white
and very very thin and tended to fountain out of the top of the skimmer.
Glass stones produced very thick brown sludge that is the desired product.
Any problems that I had with protien buildup before is now eliminated.

      Anyway, send your address and I'll get you the plans as soon as they
are done.

      Hans

In article <91077.120121HCM100-at-psuvm.psu.edu> HCM100-at-psuvm.psu.edu (Hans C.
Masing) writes:
>      I neglected to tell why I use glass airstone vice wooden.  I tried the
>wooden airstones and found that I got TOO MUCH (!?) foam.  The foam was white
>and very very thin and tended to fountain out of the top of the skimmer.
>Glass stones produced very thick brown sludge that is the desired product.
>Any problems that I had with protien buildup before is now eliminated.

If this is the case, then your skimmer is most likely mis-adjusted so that
the water level is too high.  I've found that using either limewood or
ceramic airstones, if the water level is too low, I will get very little
gunk, although the foam will still be there.  If it is too high, then the
gunk collected will be very thin and watery.

I don't understand what you mean about protein buildup.  On the insides of
the skimmer?

By the way, ceramic airstones are very similar to wooden ones functionally.
The bubbles produced, I believe, are a slight bit larger than from wooden
stones, but they don't need to be replaced nearly as often.  (Six months
as opposed to two weeks.)

patti-at-hosehead.hf.intel.com ...or just yell "Hey, Patti!"  Everybody else
does.

- --------------------------------------------------------------------------

Subject: (M) How to build a protein skimmer


                The B & R Acrylics Skimmer
                --------------------------
                                        By Rich Braun, June 1991

The importance of having a protein skimmer on just about any marine
aquarium has become acknowledged more broadly in recent years.  The
concept is an old one, borrowed from the sewage treatment industry
as is the wet/dry filter ("ammonia tower").  An undergravel filter
can accomplish the same task as a wet/dry filter, albeit less
efficiently; removal of protein-based pollutants via the process of
foam fractionation requires specialized equipment, however.  The
first documented use of this technology for fishkeeping was about
20 years ago at a public aquarium; you will now find it in use at
virtually any aquarium store worth its salt (so to speak).

A protein skimmer will benefit any marine aquarist, whether keeping
a reef tank or just a few fish.  Not only will it remove toxic
chemicals, providing reduced nitrates and better water quality, but
it will also keep the water saturated with oxygen.

Many manufacturers offer ready-made skimmers (not to be confused with
"surface skimmers" which do nothing but drain water from the surface of
the water into a filtration system) via mail-order or retail outlets,
but all have one thing in common:  extremely high price, relative to
the costs of materials and labor.  Skimmers remain relegated to the
"specialty" niche of the store and are not purchased by many aquarists;
however, they belong in every marine aquarist's filtration system.

Adding a do-it-yourself skimmer to a typical 30- to 70-gallon system
requires only a minimum of time, tools, talent, and (legal) tender.
Here's what you need for a simple air-driven counter-current external unit
with a 2-3/4" diameter, 30" high column:

Tools:
        Fine-tooth hacksaw
        Power drill
        1/2" drill bit
        1" or 1-1/4" hole saw
        Round file
        Fine sandpaper and a sanding block

Materials:
        2-3/4" acrylic tube, 30" length
        2-3/4" acrylic tube, 3" length
        3-1/2" square piece of 1/4" acrylic
        3-1/2"x4-1/2" piece of 1/4" acrylic
        2-3/4" cap for the collection cup
      * 1" plastic riser tube, 2" length
      * 1/2" PVC elbows (2)
      * 1/2" PVC T connector
      * 1/2" or 5/8" plastic hose, about 6-10 feet
        Acrylic or PVC cement
      * 3/16" rigid plastic tube, 3 feet
        Wood-block airstone

        (Asterisked items are not ozone-safe; you may want to replace
        these items with acrylic equivalents if you plan to use ozone.)

        Look in the Yellow Pages under Plastics for suppliers of
        acrylic tube; you will find 1/4" acrylic sheets at any lumber
        supply, but tube is more difficult to locate.

Prerequisites:
        As with any commercially-purchased skimmer, you will need a
        water pump and an air pump.  If you plan to use this unit
        stand-alone (without connecting into existing pumps), you can
        use the following low-cost units:

        Hagen 301 power head
        Schego Optima air pump

Construction:
        If your experience is similar to mine, you will spend more time
        on your shopping trip trying to find components than actually
        building the unit.  Here are the basic steps:

        0.  Go to a store or a friend's house and look at a real-life
            skimmer in action.  Measure its dimensions and study how
            it works.  Re-read these directions and then go on your
            shopping spree, with a $20 bill in your pocket (maybe a
            little more).

        1.  Cut out the square piece of acrylic (which will be the base)
            and the rectangular piece (which will form the bottom of
            the collection cup).  You can use an ordinary hacksaw.

        2.  Cut the 30" and the 3" lengths of acrylic tube.  You can vary
            the length of the column within certain limits:  you will
            want the overall height to fit within your space require-
            ments.  A unit which is too tall will not work properly,
            though the precise cutoff isn't known.

        3.  Sand the ends of both tubes to be *very* flat and as close
            to perpendicular as you can make them (flat is more important
            than square, to get a good seal).

        4.  Make two holes in the rectangular piece of acrylic:  a 1"
            hole centered 1-3/4" from one end, and a 1/2" hole near the
            opposite edge.  (If you are going ozone-safe, use a 1-1/4"
            outer diameter piece of acrylic tube.)  To locate the 1/2"
            hole, place the larger acrylic tube such that one edge is
            1/4" from the 1" hole, and locate the 1/2" hole just inside
            the opposite edge.  This is hard to describe without a picture;
            basically, this hole drains the collection cup, which is off-
            set from the main column:

                        |             |
                        |             | <--- Collection cup
                        | |   |       |
                        | |   |       |
                   -+-----+---+----\--\-- <-- Rectangular cup bottom
                    |             | \  \  <-- Drain
                    |             |  <-- Main column

        5.  Cut one leg off each of the elbows.  Leave about 3/4" on
            one of them; this elbow will be used for the main water
            outlet.  Cut the other one very near the angle (such that
            the remaining portion will fit through a round hole), but
            leave enough on to cause water to come out at an angle; this
            one will be used for the main water inlet.  Save one of the
            straight pieces with the nipple to use as the collection cup
            drain.  (Substitute straight 1/2" acrylic tube in this step
            to make an ozone-safe skimmer.)

        6.  Drill two 1/2" holes in the main column.  Use an old broom
            handle placed through the tube as a brace to prevent the
            acrylic from cracking.  One hole should be about 1" from
            the bottom, and the other should be about 2" from the top.

        7.  Get out your round file and/or your power drill to enlarge
            each of these holes such that they just barely fit your
            plumbing fittings.  The 1" hole should need only a little
            bit of filing in order to accomodate the 1" riser tube.

        8.  If you really want to compete with the professionals, go
            over to your gas stove and flame-polish the edges of the
            rectangles and one end of the collection cup.  Practice on
            scrap first.

        9.  You're almost finished!  Glue all the pieces together using
            acrylic cement (PVC cement, which is more widely available,
            will also work).  A diagram of the column is in order here:

                   -+-----+---+----\--\-- <-- Rectangular cup bottom
                    |             | \  \  <-- Drain
                    |             |  <-- Main column
        Inlet    ---+--           |
                 ---+--           |
                    |             |
                     ~ ~ ~ ~ ~ ~ ~
                     ~ ~ ~ ~ ~ ~ ~
                | | |             |
        Outlet  | +-+--           |
                 \--+--           |
                    |             |
                   -+-------------+-

            Mount the water inlet such that water will be aimed in a
            downward spiral direction.  Take care to avoid gaps or
            bubbles in the glue, which will cause leaky headaches later
            on.  (You can fix leaks with silicone glue but this won't
            work permanently.)  The collection cup will be removable
            if you glue it on using silicone glue; this way you can
            clean out the water column on infrequent occasions.  If
            you want a more easily removable collection cup, you can
            add an additional square piece of acrylic with a 1" hole
            in it to the top of the column and add an O-ring to seal it.
            Attach the collection cup drain nipple flush with the
            bottom, so very little (smelly) liquid will remain in the cup.

        10. Construct the water outlet tube by running a length of 1/2"
            hose vertically from the output nipple to the 1/2" T
            connector you bought, such that the water return will be
            adjustable and just below the collection cup.  The top of
            the T is an air vent, and the side is the water return:

                        |  Column   | | |
                        |           | | +--  Water return
                        |           | | +--
                        |           | | |
                        |           | | | To water outlet

            As noted below, you might want to use a larger outlet hose
            and fitting than the inlet in order to allow for greater flow.

        11. After testing the unit for water leaks, install it next
            to your tank or sump such that the water return is above
            the water level in it.  Hook up the water inlet (which is
            just under the collection cup:  you want water flowing
            downward through the column) to a small power-head or other
            source of water from the tank, and try pumping some water
            through the skimmer.  You'll probably have to play around
            with the flow rate and positioning in order to get things
            set up right; it's easy to pump water in faster than it will
            drain out.  Adjust the water outlet height such that the
            water level is about an inch or two below the collection cup.

        12. Mount the airstone on the end of a 3-foot section of rigid
            tube, and hook it up to a powerful air pump (don't mess
            with wimpy pumps; use a Shego, a Tetra Luftpump, or the
            equivalent).  Insert it into the column above the water
            outlet; you don't want bubbles entering the outlet hose.

        13. Adjust the outlet height again so bubbles are just reaching
            the bottom of the collection cup.  Make sure the cup drain
            has a hose running into a small bucket; initially you will
            want to play it safe in case the water level is too high
            (or else you might wake up to find a couple of gallons of
            salt water on the carpet!)  Monitor the outlet closely for
            the first couple of days.

        14. (Didn't want an unlucky 13 steps!)  Take your favorite
            person out to dinner, with the money you saved, to celebrate.
            Your fish will be as happy as you are.

Notes:
        This unit required about $15 worth of raw materials, and about
        3-4 hours of work (as compared to the lowest mail-order cost of
        about $80 for an equivalent unit, or retail price of about $130
        if you can find a store which doesn't want $300.)  It has now
        been operating only for a short time, so improvements in the
        design will probably be made in the future.

        The major flaw in this design is the outlet fitting size.  It
        would be better to use 5/8" fittings in order to allow for a
        more reliable drain.

        The Hagen 301 pump has much more capacity than is needed, and
        unfortunately cannot be adjusted down to 0 liters-per-hour as
        the manufacturer claims.  A small piece of tape on the "swivel
        strainer plate" as it is called in the instruction booklet
        will suffice to restrict flow to the recommended 1 to 1-1/2
        tanks of water per hour.

        The collection cup could be made of larger-diameter stock than
        the column, which would make its drain easier to construct.

        PVC fittings billed as "half-inch" really don't fit 1/2" I.D.
        hose very well; they seem to want 5/8" hose.  You don't want
        smaller fittings, though; consider getting bigger hose.

        A removable base might make for easier cleaning.  Threaded
        fittings for acrylic aren't easy to find, though; another approach
        would be to cut a hole just the size of the column in a square
        piece of acrylic, glue this around the base of the column, and
        clamp/screw the bottom square on with an O-ring.  This idea seemed
        leak-prone and somewhat difficult to construct.

        The dimensions given herein are probably adequate for a 55-gallon
        system, but larger units can be easily constructed using
        the same general guidelines.

        A skimmer may take a while to get "seasoned" with a slime
        coating, so expect to wait hours to days before you get the
        desired yucky effluent draining out of your collection cup.
        (For the 55-gallon tank to which this unit was attached after
        4-1/2 years of operating without a skimmer, yellow crud started
        dripping out within 16 hours.)

        This design is air-driven; an alternative technology calls for
        a water-driven power venturi, in which air is forced into the
        unit in much the same way gasoline enters an automobile's car-
        buretor.  Such units are more compact but generally much more
        expensive.

        Ozone (produced by a periodic spark across an air gap) can
        be used to improve the water quality even more.  This highly
        reactive substance will poison you and your fish tank if not
        used carefully:  the reason it improves water quality is that
        it destroys any biological material in its path.  This author
        has no experience with use of ozone and will therefore not
        recommend it at present; it is mentioned here only because
        skimmers must be constructed of ozone-resistant materials
        (silicone tubing, acrylic, etc.) if they are to be used with
        ozone.  Like skimmers themselves, ozonizers are also in the
        over-priced specialty category; they can probably also be
        home-built out of commonly-available raw materials.

Credits:
        Thank you to Mark Rosenstein, who helped with the design,
        construction, and shopping.

Contact:
        rbraun-at-spdcc.com, mar-at-mit.edu

- --------------------------------------------------------------------------

Subject: Construction of a Counter Current Foam Fractionator (Long)

To anyone who is considering installing a protein skimmer - DO IT!
You will be amazed at the junk it collects.

ABSTRACT
This article describes my design philosophy for constructing a couter-
current foam fractionator.  The design was admittedly seat-of-the-pants,
but seems to be functioning very well.  Complete materials, plans and
cost data is given.


APPLICATION (volumes are rated capacity)

              - 200 Gal Oceanic Saltwater tank
              - Two external flow boxes each rated at 750 GPH
              - Flow through wet-dry = 1000 Gal/Hr -at- 4ft Head


PLUMBING
My first consideration was how to plumb it to the system.  It would have 
been nice to take the inlet from the overflow and to pipe the outlet
directly to the wet-dry.  This would have ensured O2 saturation for the
wet-dry, but it would have been too difficult to plumb and still leave 
the skimmer relatively hidden behind the tank.  I opted to install Tees
(3/4" run, 1/2" branch) with 1/2" ball valves on the inlet and outlet
of my pump.  This sets up a recycle flow through the skimmer and the rate
can be precisly controled by adjusting the valves in tandem.


SIZING
My next consideration was to size the skimmer.  I did not want the it
to be excessively tall, so I felt that I needed a rather long residence
time for the water in the skimmer.  I decided (arbitrarily) that about 30
seconds should be about right.  Because of the way I plumbed the system I
only wanted about 20% of the pump outlet to go to the skimmer.  This allows
for a turnover through the skimmer of 1X per hour as opposed to the 5X per
hour through the wet-dry.  This works out to be a volume of approximately
2 Gallons for the skimmer.  Using a 3" ID for the skimmer would have
requided it to be excessivly tall.  I opted for a 4" ID which
conveniently corresponds to an approximate 36" length for the main tube.
To offset the large diameter I decided to use two (wood) air stones.
The foam riser was sized to be a 2" ID.  This approximately doubles the 
velocity of the foam.  Experimentation showed that a 12" length was
appropriate for the riser.


MATERIALS OF CONSTRUCTION
After pricing acrylic tubing, I decided that my only alternative was PVC.
I opted for Sch 40 PVC because the walls are thick enough to cut threads
into for the fittings.  Combined with epoxy glue this makes the fittings
virtually leak-proof.  PVC also has the added advantage of having many 
fittings available.  The major draw-back is that the internals of the 
skimmer are not visible.  Therefore, I can only guess at how well the 
air stones are functioning.  I did install an acrylic site glass so that 
the level could be accurately measured.


PARTS LIST (AND COST)

QTY   DESCRIPTION                        COST (EA) 
  1   10'X4"ID Sch 40 PVC Pipe           $8.50               $ 8.50
  2   4" Sch 40 End-Cap                  $3.00               $ 6.00
  2   4"x2" Sch 40 Reducers              $3.50               $ 7.00
  2   1/2" Sch 40 FNPT 90 Deg Elbow      $ .20               $  .40
  3   1/2" Sch 40 MNPTxFS adapters       $ .35               $ 1.05
  1   1/2" FNPTx 1//4"FS adapter         $ .35               $  .35
  1   1/4" FS 90 Deg elow                $ .25               $  .25
  1   3 Ftx1/4" acrillic tubing          $5.00               $ 5.00
  1   4"x10" fiberglass drain grate      $6.75               $ 6.75
  1   PVC Glue                           $2.00               $ 2.00
  2   Epoxy Glue                         $2.00               $ 4.00
  1   10' 1/2" Sch 40 PVC                $ .89               $  .89
  1   24" 2" Sch 40 PVC                  $1.00               $ 1.00
  1   15' 3/4" Tygon Tubing              $5.79               $ 5.75
  2   1/2" FNPTxFS Ball valves           $3.79               $ 7.58
----------------------------------------------------     ------------
    TOTAL                                                   $56.52



CONSTRUCTION METHOD

Part 1 - The Main Body
Cut a 36" length of the 4" PVC.  See if you can find a use for the other
84" ;-).  On the same side, drill a 3/4" hole 1" up from what will be the 
bottom and 3" down from what will be the top.  Drill another hole on the
opposite side 12" down from the top.  Cut a thread into these holes by
screwing in a 1/2" MNPT Galvanized pipe nipple or adapter.

On the bottom hole:  Take one of the 1/2" MNPTxFS adapters and coat the 
threads with with epoxy glue.  Coat the threads of one of the 1/2 "
elbows with glue.  Thread the adapter into the hole from the outside and 
screw on the elbow from the inside.  Position the elbow so that it points 
down.  Be sure to use enough glue to completely seal both sides of 
the fittings against the walls of the tube.

On the middle hole:  Use the 1/2" FNPTx1/4" FS adapter on the outside.
Use a 1/2" MNPT x FS adapter on the inside.  Glue as you did for the
bottom hole.

On the top hole:  Do this the same as the bottom hole but position the
elbow so that it points tangentialy to the wall of the tube.

Using PVC glue, glue the 4" end cap onto the bottom of the 4" tube.

Take one of the 4" by 2" reducers and ream out the inner ledge with
a file so that the 2" PVC can slide through it unrestricted.  Glue
this fitting onto the top of the tube using PVC cement.

Cut 2, 3" pipe nipples from the 1/2" PVC stock.  Glue these into the
1/2" FS fittings at the top and bottom of the tube using PVC cement.

Cut a 2" pipe nipple from the 1/4" acrylic tubing and glue it into
the reducer fitting using Epoxy glue.  Glue the 1/4" elbow on to the
other end using epoxy glue.  Orient the elbow so that it faces up.

Cut 18 inches (or more if you desire) of the clear acrylic tubing to
use as a site glass.  Glue this into the 1/4" elbow using epoxy glue.



Part 2 - The Foam Riser
The foam riser is in two parts.  A cover consisting of a piece of 4"
tubing and an end cap and a base consisting of a reducer with a drain hole
in it and the 2" riser glued in place.  The reser itselfe should NOT be
glued into the main tube.  It must be removable for cleaning; Likewise 
with the riser cover.  

Cut a 12" length of the 2" PVC off from the stock.  Take the other 4"x2"
adapter and ream it out with a file so that the 2" stock can slide through
it unrestricted.  Drill a 1/2" drain hole on the angled part of the adapter
just above where it nerrows to 2".  Cut a 3" length of the clear acrylic
tubing and glue it into this hile using Epoxy.  About 1/8" should protrude
on the inside.  Glue the 2" into the adapter using PVC glue so that 4"
of it extends above the large end of the adapter.

Cut a 7" length of the 4" PVC from the stock.  Glue an end-cap to one
end of it using PVC glue.  Drill two 1/8" holes 3/4" from the center of 
the end-cap 180 degrees from each other.  Fit the cover onto the riser
assembly.

Use some ridgid plastic air tubing and cut two lengths so that the air
stones will be above the water outlet.  Fit these through the 1/8" holes
in the top cover and through the 2" riser.  Use some flexible air tubing 
or a rubber band around them to hold them in place.  They will eventually 
need to be replaced or cleaned.  Connect the air stones fit the entire 
assembly on to the main tube.

Take the drain grate and turn it upside down ON A PIECE OF NEWSPAPER.  Fit
the bottom of the main tube into the round pipe fitting flange.  Level the
tube and shim in palce with some small wood shims.  Tack in place using 
epoxy glue.  Recheck the level and let dry.  When dry, re-glue arounf the 
entire fitting using epoxy.

Plumb up as described in the design section.  Use some flexible plastic 
tubing and run it from the drain hole in the top to a 1 Gal milk jug or
some other container.  Adjust the water level carefully so that only dry
foam spills from the riser tube.


                                ||  <--- Ridgid plastic tubing
                         _______||______
                         ||     ||    ||  <--- End cap
                          |     ||    |
                          |     ||    |
                   |      |   | || |  | <--- 4" PVC
                   |      |   | || |  | 
                   |      |   | || | <------ 2" PVC
                   |      |___| || |__|_
                   |     ||   | || |  || 
   clear           |      \   | || |   / <--- 2"x4" adapter
   acrylic   ----> |       \  | || |  /
   site-glass      |        \ | || | /\
                   |         || || ||   \  <--- clear acrylic tubing
                   |         || || ||
                   |        / | || | \
                   |       /    ||    \ <--- 2"x4" adapter
                   |      /     ||     \
                   |     ||     ||    ||
                   |      |     ||   -|--_________ <--- 1/2" MNPTxFS with
                   |      |     ||   -|--                    1/2" nipple  
                   |      |     ||  ^ |                                   
                   |      |     ||  E | 
   1/2"x1/4" --->  |____/-|--   ||  L |
   reducer with         \-|--   ||  B |
   elbow                  | ^   ||  O |
                          | 1/2 ||  W |
                          | MNPT||    |
                          |  x  ||    |
                          | FS  ||    |
                          |    -||-   |
                          |           |
                          |       |- -|--________  <--- 1/2" MNPTxFS
                          |       | |-|--               adapter with
                        |||       | | |||               nipple and
             end-cap--->||-------------||               elbow
                  ______+_______________+______  <--- drain grate



-- 
******************************************************************************
J. T. O'Beck    Litwin Process Automation              jto-at-dynsim1.litwin.com
                1250 W. Sam Houston Pkwy S.
                Houston TX, 77042

- --------------------------------------------------------------------------


RE: (m) DIY venturi skimmer request, repeated

by IN%"CHUCK-at-PIERRE.MIT.EDU" 25-MAR-1992 07:06:14.61

Subject: RE: (m) DIY venturi skimmer request, repeated

  I have built two venturi skimmers. I have to be brief I'm very
busy this week.

  for both I used powerheads. 

  For the first one I used a visijet powerhead. It was a 
in tank unit. I took a 20"x3" plexi tube open at the 
bottom, and cut a slot in the
top to accept the visijet input. The visijet was at the top
of the water level. The visijet venturi worked great, the bubles
would go almost to the bottom of the tube before turning around
and coming back up. The top of the tube served to collect the
foam. It had a small angled ledge with a drain to catch the foam
and a lid. Worked well but was in the tank.

 For the second one I used a 201 powerhead. The Venturi feature
sucked. So I drilled a small hole in the botom of the powerhead to 
allow me to put an air tube at the center of the impeller. This
makes a good venturi. I used a  24"x4" tube closed at the
bottom and added PVC elbows for an inlet and an outlet. Since
it sits in my sump it doesn't have to be perfectly water tight.
It would be watertight but I made the bottom slip on and off
for easy cleaning. A 4"x18"x1/8" plastic insert inside the tube
divdes the bottom 3/4 of tube in half. Aireated water comes
in one side up over the divider and down the otherside. You 
need to be able to adjust the flow on both the input and output.
The powerhead controls can be used for the input but a ballvalve
is nicer. Adjust the output so that the water is 1-2" higher
than the divider. The top section of tube can be cut off to
make the foam collector. Cut a 1" piece of tube and remove
2*pi*tube_thickness on one side making a braclet. If you push
the cut together the cut piece will just fit inside the uncut
tube pieces. Glue it in the top piece and now your foam collector is
removable. Add a ledge in the bottom to catch the foam.

Regards, Chuck-at-pierre.mit.edu

P.S. To drill holes for the PVC fittings you need to tightly
wedge a piece of wood in the tube so you can drill in to the wood.
Other wise you won't ge a round hole. 

- --------------------------------------------------------------------------

Dave Sheehy

[M] Home-brew Protein Skimmer Possible?

by davep-at-paladin.corp.sgi.com (David Packer)
Date: 3 Feb 1993


I'm currently building my own skimmer.  What I did was go to a place
that's local that deals with plastics.

This is what I bought and the approximate costs:

1 -  24" long 3" diameter clear acrylic tube   $10.50 // main tube
1 -   4" long 2" diameter clear acrylic tube     3.00 // cup to tube
1 -   3" long 4" diameter clear acrylic tube     4.00 // for cup
2 -   4" diameter plates + 2" dia cut in one     2.50 // for cup
1 -   3" diameter -> 2" diameter bushing         3.50 
2 - 3/4" 4" long tubes - for in/out fittings     2.50 


My tank is a 55 gal. I put the skimmer in the sump I use an
Aqua-Clear 802 to drive the skimmer. On the output side I have
a valve, that is very acurate and I use the valve to adjust the
level of the water in the column. I just finished it and it seems
to work fairly well at a fraction of the cost of a comparable skimmer.

Dave

protein skimmer design

by hagemepp-at-esu.edu (Pete Hagemeyer)
Date: 15 Jun 1994
Newsgroup: alt.aquaria

Here is a simple design for a protein skimmer, it is air driven.
the way a protein skimmer works... a fine mist of bubbles that
when rising to the surface, proteins in the water stick to them.
upon breaking at the surface (the bubbles) the proteins are
released.  It you are slightly clever you can build an apparatus
to catch all that stuff that comes out. 

Plans below ____
               |
              \ /
               ^

   [~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~]        Top View
   |         ____                  |
   |        /    \   <-- bubbles come out here
   |       |      |                |
   |        \____/                 |  <-- proteins come out here on 
   [                               ]      the tray where they are 
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~      drained or siphoned off


   [                               ]              Front view  
   |                  <-- this will be a foam   
   |       | o   o |               |
   |       |    O  |               |
   |       | o o o |               |   <-- This part collects the 
   [       |   o   |               ]       proteins, which can be
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~| |~~~       drained off.
           |   o   |          | |
           |    o  |          | |                 
           |  o    |          | |
           |     o |          | |  <-- protein drain, waste water 
          -----------                  
          -----------
           | . .. .|  
           |  : .  |  
           |  __   |                     
           | [  ]  |
           | [__]  |
           |   +   |
               +   
                 +  +  +  +   <-- airline and fine airstone 
   
A cheap solution to your needs, BTW I didn't build one yet, BUT if
YOU do, let me know how it works ok?

Later :)

-------------------------------------------------------------------
    o   \ o /  _ o         __|    \ /     |__        o _  \ o /   
   /|\    |     /\   __\o    \o    |    o/    o/__   /\     |    
   / \   / \   | \  /)  |    ( \  /o\  / )    |  (\  / |   / \  
-------------------------------------------------------------------
Program n. a magic spell cast over a computer allowing one's input
           to turn into errors.
-------------------------------------------------------------------
Feature n. a suprising property of a computer program.  A bug can
           become a feature through proper documentation. 
-------------------------------------------------------------------
Micro Credo - never trust a computer bigger that you can lift.

+-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-+
[    hagemepp-at-esu.edu     Pete Hagemeyer    East Stroudsburg U    ]
+-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-+


[M] Home-brew Protein Skimmer Possible?

by HCM100-at-psuvm.psu.edu (Hans C. Masing)

[I believe that the attribution on this one is messed up; it is
probably from HCM100-at-psuvm.psu.edu (Hans C. Masing).  If anybody
has the correct attribution, please send me another copy.--Dustin]

Ok, I got enough requests for my collection of skimmer plans to justify
reposting them. Here goes:

- --------------------------------------------------------------------------

In article <4104-at-bnr-rsc.UUCP>, dbailey-at-bcarh184.bnr.ca (Doug Bailey) says:
>Has anyone made a protein skimmer?  Could you share the plans with us?

Just so happens that I built a very efficient reverse-flow protien skimmer for
my Marine tank for under $30, uncluding the pump.

I used PVC and CPVC pipe and fittings, available REEALLLLY cheap from your
local builders supply warehouse.

A basic supply list is included below.  Prices are approximated.

      4' length of 2" PVC pipe        $3.00
      End Cap for 2" pipe             $1.25
      Screw-end adapter for 2" pipe   $1.25
      2" to 3" adapter                $1.50
      2" to 1" adapter                $ .95
      10' 1/2" CPVC pipe              $2.50
      5 - 1/2" elbows    $.12 ea      $ .60
      1 - 1/2" T-connector            $ .25
      2 - 1/2" EndCaps   $.10 ea      $ .20
      4' 3/4" vinyl hose $.60 ft      $2.40
      2 Glass Airstone                $3.00
        (Yes, Glass.  I'll explain)
      Powerhead                       ----- (Already on aquarium)
      PVC Cement (for drinking water) $4.50
      Aquarium Sealant                $3.99
      1 3/4" hose clamp (optional)    $ .27

      Tools that would be helpfull: Pipe Cutter, Electric Drill, 3/4" bit,
                                    1/8" bit, Razor blade, hammer


      I drilled two 3/4" holes in the pipe, one on one side about 8" from the
top of the tube, the other on the other side about 2" from the bottom of the
tube.  I then sealed up the bottom of the tube with the end-cap and cement.

      I cut 1" lengths of vinyl tubing and 1 1/2" lengths of 1/2" cpvc pipe.
Put the tubing in the holes in the pipe and hammer the pieces of cpvc in the
tubing, creating a very tight seal.  Make sure that enough cpvc is sticking
out of the tubing to attach elbow joints to them.

      The top hole is the water in, and the bottom is the exit.  Put an elbow
facing upwards on the bottom hole.  Cut a length of cpvc long enough to reach
to about 3" below the top of the tube and fix an elbow joint facing towards
the tank.  You can get as fancy as you like with the water return.  I made
a simple T-shaped sprinkler, using the T-joint, endcaps and 5" pieces of CPVC.
I drilled 1/8" holes along the bottom and the water sprinkled very nicely into
the tank.  IT IS VERY IMPORTANT THAT THE RETURN TUBE BE ABOUT 3" BELOW THE TOP
OF THE TUBE.  OTHERWISE YOU ARE GOING TO GET VERY WET!!  The return flow relies
on the pressure and weight of the water and the differences on the tube
diameter.  If the return tube is too high, the water will pour out of the top
of the skimmer, too low and you will never be able to collect foam.

     The foam collection cup is very simple.  Put the 1" to 2" adapter inside
the 2" to 3" adapter and glue it in place.  Also. place the 2" screw adapter
on the top of the large tube.  The foam collector should fit right over the
screw adapter, but be removable for emptying.  The collector will hold about 1
cup of foam.

      I put a bead of aquarium sealant all around the joints and inside the
foam collector.

      Use the tubing to connect the intake to your power head or other water
pump.  Be careful when first turning it on and make sure that the water level
in the skimmer remains about 2" below the top of the tube.  If it is too low,
lengthen the exit tube.  Too high, shorten it.

      Good luck, and if there are any questions, I'll try to answer them.

      Fishies rule!
      Hans

- --------------------------------------------------------------------------

Hiya everyone.

      One question that I was asked a number of times was the difference
between PVC and CPVC.  PVC is Poly-Vinyl-Chloride (I think) and is used
for plumbing and drainage.  It is white and pretty heavy duty stuff.  CPVC is
Chloro-Poly-Vinyl-Chloride (I think again) and is yellowish in color.  It is
used for drinking water supplies mostly.  Both are safe for aquarium use.  The
difference lies in the flexibility and cost, but mostly in available sizes.

      I neglected to tell why I use glass airstone vice wooden.  I tried the
wooden airstones and found that I got TOO MUCH (!?) foam.  The foam was white
and very very thin and tended to fountain out of the top of the skimmer.
Glass stones produced very thick brown sludge that is the desired product.
Any problems that I had with protien buildup before is now eliminated.

      Anyway, send your address and I'll get you the plans as soon as they
are done.

      Hans

In article <91077.120121HCM100-at-psuvm.psu.edu> HCM100-at-psuvm.psu.edu (Hans C. Masing) writes:
>      I neglected to tell why I use glass airstone vice wooden.  I tried the
>wooden airstones and found that I got TOO MUCH (!?) foam.  The foam was white
>and very very thin and tended to fountain out of the top of the skimmer.
>Glass stones produced very thick brown sludge that is the desired product.
>Any problems that I had with protien buildup before is now eliminated.

If this is the case, then your skimmer is most likely mis-adjusted so that
the water level is too high.  I've found that using either limewood or
ceramic airstones, if the water level is too low, I will get very little
gunk, although the foam will still be there.  If it is too high, then the
gunk collected will be very thin and watery.

I don't understand what you mean about protein buildup.  On the insides of
the skimmer?

By the way, ceramic airstones are very similar to wooden ones functionally.
The bubbles produced, I believe, are a slight bit larger than from wooden
stones, but they don't need to be replaced nearly as often.  (Six months
as opposed to two weeks.)

patti-at-hosehead.hf.intel.com ...or just yell "Hey, Patti!"  Everybody else does.

- --------------------------------------------------------------------------


Construction of a Counter Current Foam Fractionator (Long)

by jto-at-dynsim1.litwin.com

To anyone who is considering installing a protein skimmer - DO IT!
You will be amazed at the junk it collects.

ABSTRACT
This article describes my design philosophy for constructing a couter-
current foam fractionator.  The design was admittedly seat-of-the-pants,
but seems to be functioning very well.  Complete materials, plans and
cost data is given.


APPLICATION (volumes are rated capacity)

              - 200 Gal Oceanic Saltwater tank
              - Two external flow boxes each rated at 750 GPH
              - Flow through wet-dry = 1000 Gal/Hr -at- 4ft Head


PLUMBING
My first consideration was how to plumb it to the system.  It would have 
been nice to take the inlet from the overflow and to pipe the outlet
directly to the wet-dry.  This would have ensured O2 saturation for the
wet-dry, but it would have been too difficult to plumb and still leave 
the skimmer relatively hidden behind the tank.  I opted to install Tees
(3/4" run, 1/2" branch) with 1/2" ball valves on the inlet and outlet
of my pump.  This sets up a recycle flow through the skimmer and the rate
can be precisly controled by adjusting the valves in tandem.


SIZING
My next consideration was to size the skimmer.  I did not want the it
to be excessively tall, so I felt that I needed a rather long residence
time for the water in the skimmer.  I decided (arbitrarily) that about 30
seconds should be about right.  Because of the way I plumbed the system I
only wanted about 20% of the pump outlet to go to the skimmer.  This allows
for a turnover through the skimmer of 1X per hour as opposed to the 5X per
hour through the wet-dry.  This works out to be a volume of approximately
2 Gallons for the skimmer.  Using a 3" ID for the skimmer would have
requided it to be excessivly tall.  I opted for a 4" ID which
conveniently corresponds to an approximate 36" length for the main tube.
To offset the large diameter I decided to use two (wood) air stones.
The foam riser was sized to be a 2" ID.  This approximately doubles the 
velocity of the foam.  Experimentation showed that a 12" length was
appropriate for the riser.


MATERIALS OF CONSTRUCTION
After pricing acrylic tubing, I decided that my only alternative was PVC.
I opted for Sch 40 PVC because the walls are thick enough to cut threads
into for the fittings.  Combined with epoxy glue this makes the fittings
virtually leak-proof.  PVC also has the added advantage of having many 
fittings available.  The major draw-back is that the internals of the 
skimmer are not visible.  Therefore, I can only guess at how well the 
air stones are functioning.  I did install an acrylic site glass so that 
the level could be accurately measured.


PARTS LIST (AND COST)

QTY   DESCRIPTION                        COST (EA) 
  1   10'X4"ID Sch 40 PVC Pipe           $8.50               $ 8.50
  2   4" Sch 40 End-Cap                  $3.00               $ 6.00
  2   4"x2" Sch 40 Reducers              $3.50               $ 7.00
  2   1/2" Sch 40 FNPT 90 Deg Elbow      $ .20               $  .40
  3   1/2" Sch 40 MNPTxFS adapters       $ .35               $ 1.05
  1   1/2" FNPTx 1//4"FS adapter         $ .35               $  .35
  1   1/4" FS 90 Deg elow                $ .25               $  .25
  1   3 Ftx1/4" acrillic tubing          $5.00               $ 5.00
  1   4"x10" fiberglass drain grate      $6.75               $ 6.75
  1   PVC Glue                           $2.00               $ 2.00
  2   Epoxy Glue                         $2.00               $ 4.00
  1   10' 1/2" Sch 40 PVC                $ .89               $  .89
  1   24" 2" Sch 40 PVC                  $1.00               $ 1.00
  1   15' 3/4" Tygon Tubing              $5.79               $ 5.75
  2   1/2" FNPTxFS Ball valves           $3.79               $ 7.58
----------------------------------------------------     ------------
    TOTAL                                                   $56.52



CONSTRUCTION METHOD

Part 1 - The Main Body
Cut a 36" length of the 4" PVC.  See if you can find a use for the other
84" ;-).  On the same side, drill a 3/4" hole 1" up from what will be the 
bottom and 3" down from what will be the top.  Drill another hole on the
opposite side 12" down from the top.  Cut a thread into these holes by
screwing in a 1/2" MNPT Galvanized pipe nipple or adapter.

On the bottom hole:  Take one of the 1/2" MNPTxFS adapters and coat the 
threads with with epoxy glue.  Coat the threads of one of the 1/2 "
elbows with glue.  Thread the adapter into the hole from the outside and 
screw on the elbow from the inside.  Position the elbow so that it points 
down.  Be sure to use enough glue to completely seal both sides of 
the fittings against the walls of the tube.

On the middle hole:  Use the 1/2" FNPTx1/4" FS adapter on the outside.
Use a 1/2" MNPT x FS adapter on the inside.  Glue as you did for the
bottom hole.

On the top hole:  Do this the same as the bottom hole but position the
elbow so that it points tangentialy to the wall of the tube.

Using PVC glue, glue the 4" end cap onto the bottom of the 4" tube.

Take one of the 4" by 2" reducers and ream out the inner ledge with
a file so that the 2" PVC can slide through it unrestricted.  Glue
this fitting onto the top of the tube using PVC cement.

Cut 2, 3" pipe nipples from the 1/2" PVC stock.  Glue these into the
1/2" FS fittings at the top and bottom of the tube using PVC cement.

Cut a 2" pipe nipple from the 1/4" acrylic tubing and glue it into
the reducer fitting using Epoxy glue.  Glue the 1/4" elbow on to the
other end using epoxy glue.  Orient the elbow so that it faces up.

Cut 18 inches (or more if you desire) of the clear acrylic tubing to
use as a site glass.  Glue this into the 1/4" elbow using epoxy glue.



Part 2 - The Foam Riser
The foam riser is in two parts.  A cover consisting of a piece of 4"
tubing and an end cap and a base consisting of a reducer with a drain hole
in it and the 2" riser glued in place.  The reser itselfe should NOT be
glued into the main tube.  It must be removable for cleaning; Likewise 
with the riser cover.  

Cut a 12" length of the 2" PVC off from the stock.  Take the other 4"x2"
adapter and ream it out with a file so that the 2" stock can slide through
it unrestricted.  Drill a 1/2" drain hole on the angled part of the adapter
just above where it nerrows to 2".  Cut a 3" length of the clear acrylic
tubing and glue it into this hile using Epoxy.  About 1/8" should protrude
on the inside.  Glue the 2" into the adapter using PVC glue so that 4"
of it extends above the large end of the adapter.

Cut a 7" length of the 4" PVC from the stock.  Glue an end-cap to one
end of it using PVC glue.  Drill two 1/8" holes 3/4" from the center of 
the end-cap 180 degrees from each other.  Fit the cover onto the riser
assembly.

Use some ridgid plastic air tubing and cut two lengths so that the air
stones will be above the water outlet.  Fit these through the 1/8" holes
in the top cover and through the 2" riser.  Use some flexible air tubing 
or a rubber band around them to hold them in place.  They will eventually 
need to be replaced or cleaned.  Connect the air stones fit the entire 
assembly on to the main tube.

Take the drain grate and turn it upside down ON A PIECE OF NEWSPAPER.  Fit
the bottom of the main tube into the round pipe fitting flange.  Level the
tube and shim in palce with some small wood shims.  Tack in place using 
epoxy glue.  Recheck the level and let dry.  When dry, re-glue arounf the 
entire fitting using epoxy.

Plumb up as described in the design section.  Use some flexible plastic 
tubing and run it from the drain hole in the top to a 1 Gal milk jug or
some other container.  Adjust the water level carefully so that only dry
foam spills from the riser tube.


                                ||  <--- Ridgid plastic tubing
                         _______||______
                         ||     ||    ||  <--- End cap
                          |     ||    |
                          |     ||    |
                   |      |   | || |  | <--- 4" PVC
                   |      |   | || |  | 
                   |      |   | || | <------ 2" PVC
                   |      |___| || |__|_
                   |     ||   | || |  || 
   clear           |      \   | || |   / <--- 2"x4" adapter
   acrylic   ----> |       \  | || |  /
   site-glass      |        \ | || | /\
                   |         || || ||   \  <--- clear acrylic tubing
                   |         || || ||
                   |        / | || | \
                   |       /    ||    \ <--- 2"x4" adapter
                   |      /     ||     \
                   |     ||     ||    ||
                   |      |     ||   -|--_________ <--- 1/2" MNPTxFS with
                   |      |     ||   -|--                    1/2" nipple  
                   |      |     ||  ^ |                                   
                   |      |     ||  E | 
   1/2"x1/4" --->  |____/-|--   ||  L |
   reducer with         \-|--   ||  B |
   elbow                  | ^   ||  O |
                          | 1/2 ||  W |
                          | MNPT||    |
                          |  x  ||    |
                          | FS  ||    |
                          |    -||-   |
                          |           |
                          |       |- -|--________  <--- 1/2" MNPTxFS
                          |       | |-|--               adapter with
                        |||       | | |||               nipple and
             end-cap--->||-------------||               elbow
                  ______+_______________+______  <--- drain grate



-- 
******************************************************************************
J. T. O'Beck    Litwin Process Automation              jto-at-dynsim1.litwin.com
                1250 W. Sam Houston Pkwy S.
                Houston TX, 77042

- --------------------------------------------------------------------------

Subject: DIY Venturi plans posted here!

RE: (m) DIY venturi skimmer request, repeated

by IN%"CHUCK-at-PIERRE.MIT.EDU" 25-MAR-1992 07:06:14.61

  I have built two venturi skimmers. I have to be brief I'm very
busy this week.

  for both I used powerheads. 

  For the first one I used a visijet powerhead. It was a 
in tank unit. I took a 20"x3" plexi tube open at the 
bottom, and cut a slot in the
top to accept the visijet input. The visijet was at the top
of the water level. The visijet venturi worked great, the bubles
would go almost to the bottom of the tube before turning around
and coming back up. The top of the tube served to collect the
foam. It had a small angled ledge with a drain to catch the foam
and a lid. Worked well but was in the tank.

 For the second one I used a 201 powerhead. The Venturi feature
sucked. So I drilled a small hole in the botom of the powerhead to 
allow me to put an air tube at the center of the impeller. This
makes a good venturi. I used a  24"x4" tube closed at the
bottom and added PVC elbows for an inlet and an outlet. Since
it sits in my sump it doesn't have to be perfectly water tight.
It would be watertight but I made the bottom slip on and off
for easy cleaning. A 4"x18"x1/8" plastic insert inside the tube
divdes the bottom 3/4 of tube in half. Aireated water comes
in one side up over the divider and down the otherside. You 
need to be able to adjust the flow on both the input and output.
The powerhead controls can be used for the input but a ballvalve
is nicer. Adjust the output so that the water is 1-2" higher
than the divider. The top section of tube can be cut off to
make the foam collector. Cut a 1" piece of tube and remove
2*pi*tube_thickness on one side making a braclet. If you push
the cut together the cut piece will just fit inside the uncut
tube pieces. Glue it in the top piece and now your foam collector is
removable. Add a ledge in the bottom to catch the foam.

Regards, Chuck-at-pierre.mit.edu

P.S. To drill holes for the PVC fittings you need to tightly
wedge a piece of wood in the tube so you can drill in to the wood.
Other wise you won't ge a round hole. 


Protein Skimmer Design & the secrets of the siphon break

by tj-at-kona.cs.ucla.edu (Tom Johnson)
Date: 3 Nov 92
Newsgroup: sci.aquaria

Hello all-

Fernando Pineda <fernando-at-aplcomm.jhuapl.edu> has asked me to 
repost this article, since his attempts have all resulted in
corrupted postings.

Tom


-----------------Repost--------------------------------------

Cheap protein skimmer design & Secrets of the siphon break (long)


SUMMARY ------------------------------------------------------------------

About 1 1/2 years ago I went through the exercise of building my own 
countercurrent skimmer(s) out of PVC and CPVC pipe. I used a photograph from 
FAMA as a "blue print."  I could have bought a skimmer for what I spent in 
R&D, but I now know how to make cheap and effective skimmer. The price is more 
or less independent of the height. I also understand why a siphon break is 
important for counter current skimmers (ItUs not what you think!). 
Surprisingly, it has more to do with making the skimmer controllable than in 
preventing floods. Here are my notes. The first section is the design, the 
second section is an analysis of how a siphon break affects the stability of 
the skimmer. If you donUt like math, the bottom line is that without the 
siphon break the output valve becomes very sensitive. The sensitivity 
increases roughly in proportion to the square of the height of the skimmer.  
Without a siphon break, a 4U skimmer is very difficult (if not impossible) to 
adjust.  ItUs not hard to see why a lot of people complain about not being 
able to adjust their skimmers! Put in a siphon break and your problems will go 
away!

BUILDING A PVC SKIMMER -------------------------------------------------

PVC is much cheaper than acrylic and available everywhere.  I have never found 
any need to look inside the skimmer, in fact I suspect a PVC skimmer may be 
cleaner than an acrylic one since the lack of light prevents algea from 
growing inside the skimmer. Of the three skimmers I built, one I threw out, 
one I'm using (18" tall) and the third (4' tall) is waiting for a bigger tank. 
With no mistakes each skimmer can be made for about $30-$50 depending on how 
much you spend on valves and on whether you have to buy PVC glue, silicone, 
rubber gaskets, etc. Also IUm not counting things like drill bits, and 
hacksaws.  The basic design criteria for a homemade skimmer are:

1) The skimmer should be cheap <$50
2) Requires just a hacksaw, a power drill and a knife for construction
3) Parts are available at any hardware store
4) Easy to operate
5) Easy to keep clean


PARTS (plus lots of little things I probably forgot )----------

    4" PVC 
        1 pipe (comes in 8' sections, but a remnant is just a few dollars)
        3 RclosetS flanges (~$4 each?)
   3/4" CPVC 
       1 tube (come in 8' sections but it's just cents per foot )
       various elbows (~$0.50 ? each)
       2 CPVC adapters that go from 3/4" tubing to male threads(~$.50 each)

       2 CPVC ball values (<$5.00 each)
   3   2"-long 1/4" nylon bolts with wing nuts

   6Sx 6S Rubber sheet or O-ring
   1 rigid airline tubing ~2' length
   1 soft airline tubing ~1' length
   1 coupler for airline tubing
   2 limewood airstones + check valve

CONSTRUCTION -----------

First, assemble the skimmer, but don't glue anything. After you are sure 
everything fits, then glue it together. Do not glue the skimmer cup assembly 
to the body of the skimmer. You may have to seal the inflow/outflow 
connections on the INSIDE of the skimmer with silicone sealant to stop leaks.

1) BODY OF SKIMMER

Cut the 4" PVC pipe to the height of the skimmer (say, 18"). Attach the 
flanges to both ends of the pipe. Stand the skimmer up on one flange and punch 
out the knockout of the top flange (Closet flanges have a knockout that is not 
removed until plumbers can pressure test their connections). Now the skimmer 
is sealed at the bottom and has a 4" wide  hole at the top. Just under the 
flange (not too close) drill two holes to accommodate PVC tubing. Make sure 
your holes are ROUND otherwise they will leak. Holes should be at least 2" 
apart horizontally AND 2" apart vertically. The bottom hole is the water 
input. The top hole is the water output. 

Penetrate output hole with 4" piece of PVC tube and extend ~1/2" inside 
skimmer. Run an elbow and a 16" length of PVC tube from the output hole to the 
bottom of the skimmer (on the inside!). Make sure elbow is firmly attached to 
16" and 4" pieces of PVC. Make sure elbow is flush against the inside of the 
skimmer. With this arrangement water is fed in at the top of the water column 
and removed at the bottom ("counter current" ). 

Penetrate input hole with 1 1/2" length of PVC. Fit flush against inside of 
skimmer ...or... extend tubing 1/2 inch into skimmer and attach elbow that 
directs water current so it swirls around the skimmer. 

2) SIPHON BREAK & EXTERNAL PLUMBING

Connect elbow to outside of 4" penetrating output tube and point it downwards. 
Drill 1/8" hole through top of elbow or through top of penetrating tubing. 
Attach at least 6" of soft airline tubing to 1/8" hole with airline tubing 
coupler. Tubing must be rigid enough to stick straight up by itself.
Connect valves to input and output lines. You might need the tubing-to-threads 
adaptors. 

3) SKIMMER CUP

Take the remaining flange. Do not punch out the 4" seal, instead drill a 3/4" 
hole in the center. Lay the flange "back-to-back" on the open flange already 
on the skimmer. Attach a 3/4" coupler to the hole and insert a 4" length of 
3/4" tubing into the coupler. Cut 6" high piece of 4"-PVC pipe and connect it 
to the flange. For lack of a better name let's call this the crud-output tube. 
Notice how any liquid that comes out of the 4" tube will get caught in the cup 
formed by the flange and the 6" section of 4"-PVC pipe. Drill a drain hole in 
the SIDE of the cup near the bottom. Use whatever size tubing you want for the 
drain.  

Connect the skimmer cup to the skimmer by bolting the flanges together with 
the nylon bolts (Do not glue!). You will need either an O-ring to seal the 
connection. Buy one or make your own from either a sheet of rubber or from 
silicone sealant. Tape the airline coming from the siphon brake to the skimmer 
cup so that the opening of the airline is above the top of the cup. 

4) AIR

OK,  I forgot to explain how to put in the rigid air line. Run it through the 
top of the crud-output tube to the bottom of the skimmer.  Attach your 
limewood airstones and bolt on the skimmer cup assembly. Or, if you are 
feeling fancy you can drill a hole through the side of the skimmer, so you 
donUt have to fool with the air line when you clean the skimmer cup. Put a 
check valve in the air line.

OPERATION -------------

To start the skimmer open the output valve completely. And adjust the input 
valve until you get the desired throughput. Next, slowly close the output 
valve until the water level in the skimmer reaches the middle of the crud-
output tube. Make these adjustments slowly because the water level will 
continue to change for seconds after each adjustment. 

Start the air pump and let the skimmer run for a while. You may want to make 
further adjustments on the output valve to control the water level. 

I almost never have to adjust the skimmer. Also it's not too difficult to make 
the initial adjustments.  Major floods can't happen if your skimmer-cup-drain 
feeds into a big enough bucket. Cleaning the skimmer can be done easily by 
brushing out the crud-tube or for more serious servicing you can unbolt the 
skimmer cup assembly.


SECRETS OF THE SIPHON BREAK -------------------------------------------

HereUs a quantitative analysis to understand the importance of the siphon 
break for controlling the skimmer.  Let Rf_outS be the rate of water outflow 
and let Rf_inS be the rate of water inflow.  The water level in the skimmer is 
constant when

(1)                  f_in = f_out.

Now, letUs build a simple model for the output valve: Let the water flow 
through a valve be equal to the pressure, RpS, (AT THE VALVE!) and to the 
cross section of the valve, RAS. So 

(2)                f_out = p*A,

Let the cross-section A of the valve be proportional to RthetaS the angle 
through which you have turned the handle of the valve. So the output water 
flow is
(3)              f_out = K*p *theta

Where K is a constant of proportionality. 
Now, let RhS be the level of the water in the skimmer. If you fill the 
skimmer, open the output valve and let the water drain out, the water level 
will fall until the pressure at the valve is zero.  Let Rh_oS be the 
corresponding water level.  So for any height of water h,  the pressure at the 
valve is 

(4)              p =C*(h - h_0).

Where C is a constant of proportionality.  Finally, upon substituting (4) into 
(3) and using (1) we obtain

(5)              f_in = K*C*(h - h_0) *theta          

or
                                f_in 
(6)             theta =  _________________
                           K*C*(h - h_0) 

This equation gives the valve angle in terms of the inflow and the desired 
water height, h. Now, letUs ask the question: How much do we have to turn the 
valve to get a small change RdhS in the height of the water column? A simple 
differentiation produces
                                          f_in
(7)            d( theta) =   _  
                                    K*C*(h - h_0)^2

Where R^2S  means the quantity squared. From this expression we can conclude 
the following. The higher the water column is above h_o, the LESS one has to 
turn the valve to get a given change, dh, in the water column.  In other 
words, if (h-h_o) is large, a small change in the position of the valve 
results in a big change in the height of of the column.Now, letUs plug in some 
real numbers for the counter current skimmer described above.

First, letUs determine h_o. Suppose there is NO antisiphon attachment, then, 
as we all know, the skimmer will tend to siphon its entire contents onto the 
floor. In fact the water level in the skimmer will stop dropping  when it 
reaches the same level as the entrance to the outflow tube. LetUs say this 
leaves 2S of water in the skimmer so h_o = 2S . Now we want to maintain the 
water level somewhere near the midpoint of the crud-tube, lets say this is 
about h=22S, so (h-h_o) = 20S. 

Next, suppose we did indeed include the antisiphon. Then when we fill the 
skimmer and let it drain, the water level will fall until the antisiphon 
breaks the siphon. This will happen somewhere near the TOP of the skimmer, 
lets say this is at h_o = 18S.  So if we again want to maintain the water 
level at 22S we have (h-h_o) = 4S.

Using these two values of h - h_o in eqn. (7) we see that without the 
antisiphon, the output valve is approximately (20S/4S)^2 = 25 TIME MORE 
SENSITIVE than it is with the antisiphon valve. Furthermore the problem 
becomes more serious as the skimmer gets taller!  In fact, suppose the skimmer 
is 4U =48S high and we want to keep the water level at 48S. Assume that 
without the antisiphon,(h-h_o) = 45S and with the antisiphon,  (h-h_o) = 4S, 
then the output valve is approximately (20S/4S)^2 = 126 TIME MORE SENSITIVE 
than it is with the antisiphon valve. 

ItUs not hard to see why a lot of people complain about not being able to 
adjust their skimmers! Put in those antisiphon holes and your problems will go 
away!


-- 
Tom Johnson             "They say Confucious does his crossword with a pen."
tj-at-cs.ucla.edu                               -Tori Amos


(M) UV Sterilizer & Protein skimmer

by jmk-at-cbvox.att.com (Joseph M Knapp)
Date: Wed, 15 Jan 92
Newsgroup: rec.aquaria

In article <1992Jan14.231237.15966-at-kronos.com> you write:
>the cost of the components you need to make the skimmer will be about $20,
>available at your local plastics supplier and home-improvements store.

Rich,

A few comments that might be helpful to people asking for your plans:

	c-The plastics supplier in my case (Dayton Plastics, Columbus OH) was
	willing to cut my acrylic tubing and miscellaneous pieces to order.
	The charge was only a few bucks. So there was no sanding of edges
	to ensure a good fit. All edges glued together with no problems.

	Besides the acrylic pieces, the supplier also had acrylic glue
	and a plastic applicator bottle (sold separately) that had something
	resembling a hypodermic needle to dispense the glue. This system of 
	applying the glue was very easy, almost magic!

	I used 1" acrylic tubing into the collection cup. Problem is, I've
	only be able to locate wood airstones 3/4" square. This will not 
	fit (the ID of the tubing is 3/4"). I actually had to whittle one
	down to fit. This wasn't too hard, luckily. I wish I had used
	larger tubing though. All of this presumes that the cup is not
	removable, so the only way into the column is through the collection
	tube.

	My water return path is 1" diameter all the way and is able to carry
	at least 150 gallons/minute (this was the max output of an 802 in
	the sump, with about 3 feet of head). The column is 2-3/4" ID.
----
Joe Knapp    jmk-at-cbvox.att.com


(M) How to build a protein skimmer

by rbraun-at-spdcc.COM (Rich Braun)
Date: 28 Jun 91
Newsgroup: rec.aquaria,alt.aquaria


		The B & R Acrylics Skimmer
		--------------------------
					By Rich Braun, June 1991

The importance of having a protein skimmer on just about any marine
aquarium has become acknowledged more broadly in recent years.  The
concept is an old one, borrowed from the sewage treatment industry
as is the wet/dry filter ("ammonia tower").  An undergravel filter
can accomplish the same task as a wet/dry filter, albeit less
efficiently; removal of protein-based pollutants via the process of
foam fractionation requires specialized equipment, however.  The
first documented use of this technology for fishkeeping was about
20 years ago at a public aquarium; you will now find it in use at
virtually any aquarium store worth its salt (so to speak).

A protein skimmer will benefit any marine aquarist, whether keeping
a reef tank or just a few fish.  Not only will it remove toxic
chemicals, providing reduced nitrates and better water quality, but
it will also keep the water saturated with oxygen.

Many manufacturers offer ready-made skimmers (not to be confused with
"surface skimmers" which do nothing but drain water from the surface of
the water into a filtration system) via mail-order or retail outlets,
but all have one thing in common:  extremely high price, relative to
the costs of materials and labor.  Skimmers remain relegated to the
"specialty" niche of the store and are not purchased by many aquarists;
however, they belong in every marine aquarist's filtration system.

Adding a do-it-yourself skimmer to a typical 30- to 70-gallon system
requires only a minimum of time, tools, talent, and (legal) tender.
Here's what you need for a simple air-driven counter-current external unit
with a 2-3/4" diameter, 30" high column:

Tools:
	Fine-tooth hacksaw
	Power drill
	1/2" drill bit
	1" or 1-1/4" hole saw
	Round file
	Fine sandpaper and a sanding block

Materials:
	2-3/4" acrylic tube, 30" length
	2-3/4" acrylic tube, 3" length
	3-1/2" square piece of 1/4" acrylic
	3-1/2"x4-1/2" piece of 1/4" acrylic
	2-3/4" cap for the collection cup
      *	1" plastic riser tube, 2" length
      * 1/2" PVC elbows (2)
      * 1/2" PVC T connector
      *	1/2" or 5/8" plastic hose, about 6-10 feet
	Acrylic or PVC cement
      * 3/16" rigid plastic tube, 3 feet
	Wood-block airstone

	(Asterisked items are not ozone-safe; you may want to replace
	these items with acrylic equivalents if you plan to use ozone.)

	Look in the Yellow Pages under Plastics for suppliers of
	acrylic tube; you will find 1/4" acrylic sheets at any lumber
	supply, but tube is more difficult to locate.

Prerequisites:
	As with any commercially-purchased skimmer, you will need a
	water pump and an air pump.  If you plan to use this unit
	stand-alone (without connecting into existing pumps), you can
	use the following low-cost units:

	Hagen 301 power head
	Schego Optima air pump

Construction:
	If your experience is similar to mine, you will spend more time
	on your shopping trip trying to find components than actually
	building the unit.  Here are the basic steps:

	0.  Go to a store or a friend's house and look at a real-life
	    skimmer in action.  Measure its dimensions and study how
	    it works.  Re-read these directions and then go on your
	    shopping spree, with a $20 bill in your pocket (maybe a
	    little more).

	1.  Cut out the square piece of acrylic (which will be the base)
	    and the rectangular piece (which will form the bottom of
	    the collection cup).  You can use an ordinary hacksaw.

	2.  Cut the 30" and the 3" lengths of acrylic tube.  You can vary
	    the length of the column within certain limits:  you will
	    want the overall height to fit within your space require-
	    ments.  A unit which is too tall will not work properly,
	    though the precise cutoff isn't known.

	3.  Sand the ends of both tubes to be *very* flat and as close
	    to perpendicular as you can make them (flat is more important
	    than square, to get a good seal).

	4.  Make two holes in the rectangular piece of acrylic:  a 1"
	    hole centered 1-3/4" from one end, and a 1/2" hole near the
	    opposite edge.  (If you are going ozone-safe, use a 1-1/4"
	    outer diameter piece of acrylic tube.)  To locate the 1/2"
	    hole, place the larger acrylic tube such that one edge is
	    1/4" from the 1" hole, and locate the 1/2" hole just inside
	    the opposite edge.  This is hard to describe without a picture;
	    basically, this hole drains the collection cup, which is off-
	    set from the main column:

			|             |
			|             |	<--- Collection cup
			| |   |       |
			| |   |       |
		   -+-----+---+----\--\-- <-- Rectangular cup bottom
		    |             | \  \  <-- Drain
		    |             |  <-- Main column

	5.  Cut one leg off each of the elbows.  Leave about 3/4" on
	    one of them; this elbow will be used for the main water
	    outlet.  Cut the other one very near the angle (such that
	    the remaining portion will fit through a round hole), but
	    leave enough on to cause water to come out at an angle; this
	    one will be used for the main water inlet.  Save one of the
	    straight pieces with the nipple to use as the collection cup
	    drain.  (Substitute straight 1/2" acrylic tube in this step
	    to make an ozone-safe skimmer.)

	6.  Drill two 1/2" holes in the main column.  Use an old broom
	    handle placed through the tube as a brace to prevent the
	    acrylic from cracking.  One hole should be about 1" from
	    the bottom, and the other should be about 2" from the top.

	7.  Get out your round file and/or your power drill to enlarge
	    each of these holes such that they just barely fit your
	    plumbing fittings.  The 1" hole should need only a little
	    bit of filing in order to accomodate the 1" riser tube.

	8.  If you really want to compete with the professionals, go
	    over to your gas stove and flame-polish the edges of the
	    rectangles and one end of the collection cup.  Practice on
	    scrap first.

	9.  You're almost finished!  Glue all the pieces together using
	    acrylic cement (PVC cement, which is more widely available,
	    will also work).  A diagram of the column is in order here:

		   -+-----+---+----\--\-- <-- Rectangular cup bottom
		    |             | \  \  <-- Drain
		    |             |  <-- Main column
	Inlet	 ---+--           |
		 ---+--           |
		    |             |
		     ~ ~ ~ ~ ~ ~ ~
		     ~ ~ ~ ~ ~ ~ ~
	        | | |             |
	Outlet  | +-+--           |
		 \--+--           |
		    |             |
		   -+-------------+-

	    Mount the water inlet such that water will be aimed in a
	    downward spiral direction.  Take care to avoid gaps or
	    bubbles in the glue, which will cause leaky headaches later
	    on.  (You can fix leaks with silicone glue but this won't
	    work permanently.)  The collection cup will be removable
	    if you glue it on using silicone glue; this way you can
	    clean out the water column on infrequent occasions.  If
	    you want a more easily removable collection cup, you can
	    add an additional square piece of acrylic with a 1" hole
	    in it to the top of the column and add an O-ring to seal it.
	    Attach the collection cup drain nipple flush with the
	    bottom, so very little (smelly) liquid will remain in the cup.

	10. Construct the water outlet tube by running a length of 1/2"
	    hose vertically from the output nipple to the 1/2" T
	    connector you bought, such that the water return will be
	    adjustable and just below the collection cup.  The top of
	    the T is an air vent, and the side is the water return:

			|  Column   | | |
			|	    | | +--  Water return
			|           | | +--
			|           | | |
			|           | | | To water outlet

	    As noted below, you might want to use a larger outlet hose
	    and fitting than the inlet in order to allow for greater flow.

	11. After testing the unit for water leaks, install it next
	    to your tank or sump such that the water return is above
	    the water level in it.  Hook up the water inlet (which is
	    just under the collection cup:  you want water flowing
	    downward through the column) to a small power-head or other
	    source of water from the tank, and try pumping some water
	    through the skimmer.  You'll probably have to play around
	    with the flow rate and positioning in order to get things
	    set up right; it's easy to pump water in faster than it will
	    drain out.  Adjust the water outlet height such that the
	    water level is about an inch or two below the collection cup.

	12. Mount the airstone on the end of a 3-foot section of rigid
	    tube, and hook it up to a powerful air pump (don't mess
	    with wimpy pumps; use a Shego, a Tetra Luftpump, or the
	    equivalent).  Insert it into the column above the water
	    outlet; you don't want bubbles entering the outlet hose.

	13. Adjust the outlet height again so bubbles are just reaching
	    the bottom of the collection cup.  Make sure the cup drain
	    has a hose running into a small bucket; initially you will
	    want to play it safe in case the water level is too high
	    (or else you might wake up to find a couple of gallons of
	    salt water on the carpet!)  Monitor the outlet closely for
	    the first couple of days.

	14. (Didn't want an unlucky 13 steps!)  Take your favorite
	    person out to dinner, with the money you saved, to celebrate.
	    Your fish will be as happy as you are.

Notes:
	This unit required about $15 worth of raw materials, and about
	3-4 hours of work (as compared to the lowest mail-order cost of
	about $80 for an equivalent unit, or retail price of about $130
	if you can find a store which doesn't want $300.)  It has now
	been operating only for a short time, so improvements in the
	design will probably be made in the future.

	The major flaw in this design is the outlet fitting size.  It
	would be better to use 5/8" fittings in order to allow for a
	more reliable drain.

	The Hagen 301 pump has much more capacity than is needed, and
	unfortunately cannot be adjusted down to 0 liters-per-hour as
	the manufacturer claims.  A small piece of tape on the "swivel
	strainer plate" as it is called in the instruction booklet
	will suffice to restrict flow to the recommended 1 to 1-1/2
	tanks of water per hour.

	The collection cup could be made of larger-diameter stock than
	the column, which would make its drain easier to construct.

	PVC fittings billed as "half-inch" really don't fit 1/2" I.D.
	hose very well; they seem to want 5/8" hose.  You don't want
	smaller fittings, though; consider getting bigger hose.

	A removable base might make for easier cleaning.  Threaded
	fittings for acrylic aren't easy to find, though; another approach
	would be to cut a hole just the size of the column in a square
	piece of acrylic, glue this around the base of the column, and
	clamp/screw the bottom square on with an O-ring.  This idea seemed
	leak-prone and somewhat difficult to construct.

	The dimensions given herein are probably adequate for a 55-gallon
	system, but larger units can be easily constructed using
	the same general guidelines.

	A skimmer may take a while to get "seasoned" with a slime
	coating, so expect to wait hours to days before you get the
	desired yucky effluent draining out of your collection cup.
	(For the 55-gallon tank to which this unit was attached after
	4-1/2 years of operating without a skimmer, yellow crud started
	dripping out within 16 hours.)

	This design is air-driven; an alternative technology calls for
	a water-driven power venturi, in which air is forced into the
	unit in much the same way gasoline enters an automobile's car-
	buretor.  Such units are more compact but generally much more
	expensive.

	Ozone (produced by a periodic spark across an air gap) can
	be used to improve the water quality even more.  This highly
	reactive substance will poison you and your fish tank if not
	used carefully:  the reason it improves water quality is that
	it destroys any biological material in its path.  This author
	has no experience with use of ozone and will therefore not
	recommend it at present; it is mentioned here only because
	skimmers must be constructed of ozone-resistant materials
	(silicone tubing, acrylic, etc.) if they are to be used with
	ozone.  Like skimmers themselves, ozonizers are also in the
	over-priced specialty category; they can probably also be
	home-built out of commonly-available raw materials.

Credits:
	Thank you to Mark Rosenstein, who helped with the design,
	construction, and shopping.

Contact:
	rbraun-at-spdcc.com, mar-at-mit.edu
------


homebrew skimmers

by richb-at-kronos.com (Rich Braun)
Date: 1 Dec 91
Newsgroup: rec.aquaria,alt.aquaria

laurence-at-cco.caltech.edu (Dustin Lee Laurence) writes:
>I don't really know how to either estimate or make adjustable
>the size of the tube from the top of the water column to the collection cup.

Well, my own approach was to merely copy the dimensions of a commercially-
built skimmer.  I'm sure there are scientific ways to calculate the
various dimensions.

For what it's worth, my own home-brew skimmer has a 30" high water column,
2-1/2" internal diameter.  The collection cup is rigidly attached to this
column (making for slightly less convenient cleaning--I have to pull the
whole unit), and employs a 2" long segment of standard 1" airlift tube for
the component you describe.  The bottom of this tube is flush with the
bottom of the horizontal plate capping the main water column.

Were I to build a higher-capacity skimmer, I would go to either a 4" or
6" column, and use approximately a 1-1/2" collection tube.  The height
of this tube does matter, and short of measuring a commercially-built one
I don't know how to recommend determining this.

-rich


(m) Venturi Skimmer valves

by perry-at-cbmvax.commodore.com (Perry Weinthal)
Date: 26 Mar 92
Newsgroup: rec.aquaria,alt.aquaria

In article <1992Mar24.210935.1-at-pomona.claremont.edu> efang-at-pomona.claremont.edu writes:
> DIY Venturi skimmers plans...

  The Water Bed industry is another source of venturi valves.
These widgets have in most cases "garden hose" fittings, which are not
the same as PT (pipe thread). These venturi drain water beds using Tap
water to create a vacum, which is then connected to the bed's fill plug
via a garden hose. 

Note: Most units are All plastic, what type I do not know. 

 Perry Weinthal 
 perry-at-cbmvax


Skimmy Information

by ahughes-at-arch386.hyperdesk.com (Arch Hughes)
Date: 22 Jun 92
Newsgroup: alt.aquaria,rec.aquaria


    I got a couple of "I'd like to know"s back from my note about my
protein skimmer of late last week.  A miracle happened, and I
remembered this morning to get the write up out of the Skimmer box
before I came to work.  Here is some of the information from the
sheet that came with the device.

    Contact Monty at Aquarium Technologies, 1-206-943-4366, 
    1100 to 1800 PST, Monday through Friday.

    Model   Needed Depth    Rated Size[1]

     10         10"         <40 gal
     15-S       10"         <40 gal
     15         12"         <75 gal
     15-L       18"         <125 gal

    [1] Sheet states: "For sensitive animals and corals these
guidelines are high, for fish-only tanks, low.

    The top fitting rises about 3" above the water.

    They say they ship UPS within 3 working days.  Guaranteed for 6
months, money back or exchange (your choice, it says) for any reason. 

    The instructions say you should have a good strong pump
recommended by your pet store, or buy a Tetra Luft pump.
    
    For sizing, here's what mine looks like (my protein skimmer, I
mean 8-)).  (I'm the world worst at such pictures, so don't expect too
much!)





                Air Line 1

                    |            |
    PVC Elbow       |            |            
         -----------|-|          |            
         |          | |          |
         |  ------  | |          |
         |  |     | | |          |
         |  |     | | |          |
   Waste |  |     | | |          |
    Out  |  |   |---|---|        | Air Line 2
     |   |  |   |---|---|        |
     V   |--|   |   |   |        |                  
                |   |   | ~~~~~~ | ~~~~~~~~~~~~~~~~~  Approx Water Level
                |   |   |        |
                |   |   |        |
                | --|-- |        |
                | | | | |        |
       Water    | | | | |        |
      Intake    | --|-- |        |
       Hole     |   |   | |\     |
                |   |   | | \    |
                |   |   | |  \   |
                |   |   | |   |  |
                |   |   | |   |  |
      Reaction  |   |   | |   |  |  Air
        Tube    |   |   | |   |  |  Lift
                |   |   | |   |  |  Tube
                |   |   | |   |  |
                |   |   | |   |  |
                |   |   | |   |  |
                |   |   | |   |  |
                |   |   | |   |  |
                |   |   | |   |  |
                |   |   | |   |  |
                |  ---  | |   |  |
                |  | |  | |   |  |
       Limewood |  | |  | |   | /
      Air Stone |  | |  | |   |/
                |  | |  | |  /|
                |  | |  | |   |
                |  | |  | |   |
                |  ---  | |   |
              |--       --|   ||
              |                |
              |----------------|



    Hey...that's not too bad!  The reaction tube is 1 1/8 " tubing.
The waste out tube goes about 2" out from the reaction tube.  As
stated above, the unit rises about 3" above the water.  That height is
an adjustment you make (by moving the unit up and down in the water)
to get just right output of waste, not water, coming out.

    Here's some description to help you see it.  The reaction tube is
1 1/8 " clear tubing.  It has a water intake hole about 1/3 the way
down (shown square here, but actually round as if drilled) on both
sides.  A stiff air tube goes down through the center of the reaction
tube holding a limewood air stone.  It runs up through a sealed clear
top and a white PVC double elbow (180 degree bend).  This air tube and
stone, of course, causes the foaming.  The foam goes up the tube, past
the water intake hole, and will go through the hole into the top and
into the PVC elbows if stable enough.  If it makes the second bend it
runs down the waste out tube, to which some 1/2 clear silicon tubing
is attached and into a collection jar.

    Air line two runs the water flow.  Air is pumped into the smaller
tube (shown on the right) and bubbles up and out the angle cut top.
It causes water to enter via the water intake port, flow down the
reaction tube (mixing with the foam that's going up the reaction
tube), down around the connector on the bottom, and up with the large
bubbles in the lift tube on the right.  So, the water flows in a U
shape...down on the left and up on the right.

    The double elbows are shown going off to the left.  As the top can
be rotated, they could go off in any direction.  The elbows allow the
waste connection to go down outside the tank.  The unit has a couple
of suction cups (not shown) near the bottom and about half-way up,
that stick it to the internal wall of the tank.  They can be attached
to any of three sides (not the side with the lift tube).  There is a
rubber band (not shown) that fits over the reaction tube and the waste
down tube connector.  It provides a "height safety" so that if the
cups come off the wall the unit won't drop into your tank any further
than the rubber band (or it would probably flood your floor by
starting a siphon in the waste down tube to your collection jar).

    The connector on the bottom and the top of the reaction tube
appear to be "specialty" pieces.  Other than that it all looks pretty
standard and DIY.

    I've got the model 15 for my 35 gallon tank.  I paid $35 for it at
my local pet store (air pump not included).  I'd be interested to know
what Monty wants for one.  I'm getting a new piece of 1 1/8" tubing to
extend the reaction tube further in my tank.  I'll try and put it
almost all the way to the bottom and get about 20" of reaction tube
length.  It seems to work very well now, but tinkering is just in my
nature and I like to keep fixing things until they break (sort of the
Peter Principle of Engineering).

-- 
o o|  Arch Hughes, HyperDesk Corp.        Phone   508-366-5050 x103
o o|  Suite 300, 2000 West Park Dr.       Fax     508-898-3841
---+  Westboro, MA   01581                E-Mail  arch-at-hyperdesk.com


DIY Venturi skimmer - anyone done this ?

by kncarp-at-nicsn1.monsanto.com (Kevin N. Carpenter)
Date: Thu, 18 Feb 1993
Newsgroup: rec.aquaria

Robert Ivan (rivan-at-bnr.ca) wrote:
: In article <1993Feb18.161510.29798-at-bmerh85.bnr.ca>, rivan-at-bnr.ca (Robert Ivan) writes:
: |> 
: |>  There have been lots of postings for do it yourself columnar
: |> protein skimmers but what about venturi skimers?  I have already

A few net friends and I had an extended discussion on air-driven vs.
venturi skimmers.  Our research found out several interesting facts:

Most venturi valves require a significant pressure drop in order to
function.  Call significant at least 5 PSI, with 10 PSI or more allowing
greater flexibility.  This eliminated using pumps like Quiet Ones,
which cannot generate signficant flow at high pressure.

Back pressure of even 1 PSI can easily half the amount of air delivered
by a venturi valve.  This appears to be the main reason most venturi
skimmers are designed to release their water into the TOP of a skimmer.
A 2' column of water generates close to 1 PSI of backpressure...

Water delivery requirements were fairly high, especially when combined
with the pressure requirements.  Most of our studies were considering
MD-4 to MD-5 class pumps in order to provide reasonable pressure.  Note
that these pumps burn significant power, uping operating cost.  One
realization that come from this was that a venturi based skimmer will
probably always cost more to operate (in terms of power used) than an
air based system, since the motive material, water, is 40 times denser
than air.  More mass to move, requires more power...

Actual air mixing capability of venturi valves vs. high-quality air stones
remains unknown.  We did not come up with any measureable method to 
generate any metrics.

Oh well, after several weeks of discussion, I decided to build a 6' 
counter-current air-based skimmer (powered by a Medo pump (which has just
been ordered)).  Note that both styles of skimmer will work, as will
a straight co-current skimmer.  The difference is efficiency and operating
cost.

--
Kevin Carpenter       Internet:  kncarp-at-nicsn1.monsanto.com
Monsanto Company      Fidonet:   1:100/215.0 (home)
St. Louis, Missouri, U.S.A.
Opinions expressed are those of the author, not the company he works for. 


home brew skimer plan

by rivan-at-bcarh970.bnr.ca (Robert Ivan)
Date: 17 Jan 1994
Newsgroup: rec.aquaria

  Ok so i tok some time to punch out a rough sketch of a skimmer of mine.
Its not complete but simple enough.


materials :   acrylic tube 2 - 3 inch diameter (extuded is cheapest)
              cpvc 1/2 or 3/4 inch piping  ( the white stuff)
              flexible hose ( any type you like)


 Description :  This skimmer is from acrylic.  One could use PVC which is
                 easyier to work with and chaeper but you cant see inside.
                To weld acrylic is easy using a solvent called Methyl-chloride
                which can be got from a plastic shop ( hwre youll get the 
                 acrylic also-- just ask for instuctions on how 
                 to use the stuff.



all measuments are rough and in inches.


                       ___________________
                      |                   | ----- plastic pipe cap ( for pvc)
                      | |               | |
                        |               |
                        |    |   |      |  <-  acrylic tube say 4 inches height
			|    |   | <------------- smaler pipe 2.5  high	|
			|    |	 |	|
		_____________|   |_____________  plastic plate ( use 1/4 thicK)
		       	|	^	|		
			|	|	| ^
			|	hole	| | 2 inches				
		  3 inches	|		| ^
			|		__		
			|		__  <- inlet ( use pvc  )		
			_____		|
		<----	___  |		|
		out	|  | |		| <- acrylic tube 18 inches at least		
			|  | |		|	
			|  | |		|	
			|  | |		|		
			|  | |		|
			|  | |	|	|	
		-------- > | |	|	|
		cpvc 	|  | |	| <------- airline or rigid tube (1/4 D acrilic	
		pipe	|  | |	|	|	
			|  | |	|	|
			|  | |	|	|
			|  | |	#	|
			|  | |	# <-------------- airstone ( 		
			|	#	|
               _________________________________ another plate
			


  Thats pretty much it.  My skimmers have threaded connectors on the
input and output ends to which I  connect barbs and  flexible hose. 
Also I would recomend GOOP ( like sylicone but thats the name) applyied
around the acrylic welds to seal it.  The level of foam is controled 
by a valve on the input side.  Anyway the above produces a reasonable
counter current skimmer and if done right just as good as anything 
bought. If the above seems vague i recomend looking at one in the store or
blowing up a picture of one in Fama ( you could photocopy  one into
the right size and that would give you a scale picture).  If its still
not too obvious dont attempt it because you may have no
mechanicle ability and trying to build it yourself may be disastrous.
Note that if its not built solid enough it could explode ( this happened 
to me ) and empty your entire sump contents on the floor.  So always
test the skimmer in a bucket for a few days.  If you build the skimmer
entirley from PVC then it might hold together better.  I recomend an
hour or so in a hardware store puting together the PVC elbows etc
to get an idea of the plumbing.  Also a PVC (plack sewer pipe) skimmer
can be entirely built from parts in the plumbing section. I bet a 5 ft model would only be about $40. 
 



ROB 
-excuse the typos please


home brew skimer plan

by rivan-at-bcarh970.bnr.ca (Robert Ivan)
Date: 17 Jan 1994
Newsgroup: rec.aquaria

   One thing I left out.  If you show this plan to a plastics shop
they may be willing to show you how to build it.  My store cuts all
the parts (except the PVC) and just charges for materials.  They should
be able to show you how to weld the parts. See Plastic in the Yellow Pages.
You might be able to get them to build one ( only worth it if its a big one)
for a lot less than one from a store.


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