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  1. [F][PLANTS] A story of one DIY CO2 system.
    by hopea-at-cs.Helsinki.FI (Pauli Hopea) (18 Feb 92)

[F][PLANTS] A story of one DIY CO2 system.

by hopea-at-cs.Helsinki.FI (Pauli Hopea)
Date: 18 Feb 92

 I finally got my DIY CO2 system together. The system I have is somewhat
different than those explained here before, so I'll describe it here.

 First of all, I want to thank Vinny Kutty for helping me with
this project. Thanks a lot, Vinny!

 The basic idea was to get a automatic CO2 injection with minimum
of cost (of course :) ).

 I learned that the gas cylinder is a major cost in this project. So I
was lucky to find 27 CO2-gas cylinders in one auction (half of them were
full). The cylinders were small, 300grams of CO2, but it seems to be
enough. One cylinder should last about 3-4 months. One advantage is the
small size. The cylinder fits easily into my cabinet. The other
advantage is that since I have more than one cylinder, I can have the
system running all the time, also when the other cylinders are getting
refilled. And there is no hurry to do the refill.

 My friend happened to have a regulator for a CO2-cylinder, and I got it
for free, since he needed one with gauges and this one did'nt have them.

 Next happy coincident was that I had once bought something from another
auction, and there was a few boxes of hydraulic stuff along. I had
almost forgotten those, and when I checked the boxes out, there was
lots of needle valves in there! And these valves had the same thread
that was in the regulator outlet!

 I was astonished by the price of the silicone tubing. Re-inforced
tubing was $16/meter ! Well, since I had tubing only after the
valves, I could use normal tubing which was only $4/meter.

 Then it was time to put all the stuff together. I had a small problem
with the cylinder/regulator fitting. These cylinders have no valve to
open/close the cylinder. Instead they have a needle valve (same kind
that is in car tires). My regulator did'nt push the needle down so I
had to saw a little cut in the regulator and glue a small spike in
that cut across the hole. It needed a little adjustment but I was able
to fix the regulator so that it pushed the needle down exactly the same
time the fitting was tightening, so I would not lose CO2 when changing

 Since I had no gauges in the regulator I took a simple gauge (from
a car shock absorber system, it had the same thread :) and fitted one
needle valve to the regulator outlet (so I could close the flow)
and fitted the cauge in the valve. Then I just adjusted the pressure
to ~2psi, taped the adjustment screw in place, shut the valve and
took the cauge off.

 There is no need to get expensive regulators with gauges if you just
are able to adjust the regulator once. It would be useful to know the
cylinder pressure, but since I can see (and hear) the bubbles, have many
cylinders and will eventually know how long one cylinder lasts, that
will be no big problem.

 Then I fitted two more needle valves to be able to regulate the flow,
then a hose fitting to the valve and the hose in it.

 I made the reactor from a small (4 watt) fluval inside filter I had:
(better draw a picture, I'm not good at explaining this in english)


                 _______  ||
             <= |       | ||
                | motor | ||
                |_ _____| ||
                | ^     | ||
                | ^    _|_||
                |      ____|  L-fitting
                |       |
             => |_______|<=

 This reactor seems to work ok. I can see the bubbles to regulate the
flow. The impeller breaks the bubbles into pieces (sounds like 'ptufff')
and most of the small bubbles dissolve before they reach the surface
(50 cm tall tank). Later, I might add an upturned jar in front of the
outlet (in ~45 angle) to keep the bubbles in water a little longer.

 It was time to test everything. I put the reactor behind a driftwood,
plug it into the light timer, used the two valves to get suitable
flow (about 1 bubble/6 sec) and voila'. Then I sank the regulator and
valves to a water bucket to check for leaks (had to tighten a few
joints). I begun wondering why the bubbles did'nt dissolve at all.
I collected some gas from the outlet into a jar and nothing of it
dissolved! I was sure all the air in the tubing was long gone.
After consulting Vinny I decided to check this with another gas
cylinder and yes! this first cylinder had pressurized air in it,
not CO2. Second cylinder had CO2 and it dissolved well. I checked
all the other cylinders, and noticed, that the 'air cylinder' had no
extra labels in it. Others had 'CO2, filled by....' in them. The firm
had used this one cylinder probably to have pressurized air to clean
things. Good thing that I noticed this when testing everything.

 These cylinders are used in soft drink machines, so I was sure nobody
would use them for anything else than CO2 or air. Since some other gas,
than air, would need to be filled by a dealer, and they would not do
that. So it was easy to check if the gas would dissolve (CO2)
or not (air).

 Now that I have the system running, I will get a solenoid from
one hydraulic shop ($35) because it will fit straight into the
place where I have the first valve, and the solenoid they sell, is
a very neat one: the valve and solenoid can be separeted, so you can
change the solenoid (12V, 110V, 220V) if you need to. I'll get the
220V so that I can plug the solenoid straight into the light timer.

 Now I'm going to put together few of these systems, and find out
if there are other plant-nuts around here.


human-net:  Pauli Hopea          I ....and the last thing that was left
voice:     +358-0-7522953        I     was light. Then God pulled the plug,
email:      Hopea-at-cc.Helsinki.Fi I     and then there was nothing.

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