You are at The Krib ->Plumbing and Filtration [E-mail]

DIY Trickle Filter - Blackford


  1. DIY trickle filter plan
    by (Matthew J Blackford) (Sat, 1 Oct 1994)

DIY trickle filter plan

by (Matthew J Blackford)
Date: Sat, 1 Oct 1994
Newsgroup: rec.aquaria

Here are the plans for a DIY trickle filter.  Id be happy to answer any
questions or go into greater detail if anybody is working on a similar


|      ** sponge       |
|~~~~~~||~~~~~~~~~~~~~~| water level
|      ||standpipe     |
|      ||              |                                      TANK
      {||}pvc bulkhead fitting
       [] flexible hose
       []          ball valve
        []        _T_   __
         [][]====<___>=|_ \
                   ______||______  pvc fitting
                  [_____{||}_____] bucket lid
                   |************|  prefilter pad
                   |XXXXXXXXXXXX|  eggcrate          
      |            |[..........]|  drip tray             |
      |            |000000000000|                        |    FILTER
      |            |000000000000|  bioballs              |
      |            |000000000000|                        |
      |~~~~~~~~~~ ||XXXXXXXXXXXX|| eggcrate ~~~~~~~~~~~~~|
      |           |              |               ___||_  |
      |           |              | stand         |_____= |
      |           |()__()__()__()|                pump   |

        40g breeder I found at a pet store for $20 with a 1" hole drilled
        in the bottom for a drain.  Inhabitants are med. sized S. American

Water feed:   

        With a hole in the bottom, a trickle filter system with a sump
        is easily made.  I chose to use 3/4" pvc as a standpipe attached
        to a pvc bulkhead fitting.  The fitting is mad from male and 
        female threaded pvc fittings and sealed with silicone.  The 
        standpipe reaches to the level where the water will be in the 
        tank.  This type of system avoids some of the problems associated
        with siphon overflows since the level in the tank cannot get
        any higher than the height of the standpipe- unless the pipe
        is clogged.  

*note*  The water level actually is a little above the height of the
        standpipe.  I -did not- glue the pipe to the fitting on the bottom
        of the tank so I could remove the pipe and make adjustments in
        the water level.  The pipe only fits snugly in the fitting in
        the bottom of the tank.  In the top of the pipe I filed four
        slots similar to the skimming teeth in an overflow box and
        put half of an Aquaclear sponge on the top of the pipe to prevent
        the pipe from clogging causing the tank to overflow.

                            =====|  |
           standpipe             | =|  <--notches cut with a file
                            =====|  |

        A 1" ID flexible hose is attached to the fitting on the outside
        bottom of the tank feeding the water to the trickle filter.


        The filter is made from a 5 gal bucket.  The bottom of the bucket
        is about 12" in diameter.  An 11" hole was cut in the bottom of 
        the bucket, leaving a small rim on the inside.  I cut eggcrate
        (light diffuser for flourescent light fixtures) to fit on this
        rim.  The bioballs are supported by this eggcrate.
        The flexible hose feeding the water to the filter is attached
        to a ball valve (used to turn off the water if the standpipe
        needed cleaning, etc.)  The outlet of the ball valve is attached
        to a threaded elbow which is threaded into a female pvc fitting 
        throught the center of the bucket lid.
        The water then falls through a prefilter pad set on another piece
        of eggcrate with rests on the top of the drip tray.  The drip tray
        is the bottom of a 5gal bucket with an 11" hole cut in the bottom
        similar to the filter housing except the bottom 2" of the bucket
        is cut off to form a 2" deep tray.  Then I cut a 12" circle of
        1/4" acrylic to fit inside the tray and drilled 3/32" holes on
        a 3/4" grid.  I did not drill holes in the center 3" of the acrylic
        since this is where the water will directly splash.  The acrylic
        was then glued with silicone into the tray to complete the drip
        tray.  The drip tray is set on top of the bioballs.

*note*  The water in the drip tray should have some measurable depth so the
        water is dispersed fairly evenly even if the tray is not completely
        level.  The size of the holes needed depend on the flow of the
        water to the filter.  I got lucky the first time with 3/32" holes-
        the water feed keeps the level in the tray at about 1" allowing even
        dispersion but not overflowing over the sides of the drip tray.
        Start by drilling small holes - you can always make them larger if
        the flow through the tray is too low.

        The stand for the filter is made from the top part of the bucket 
        that the drip tray is made from.  Just simply turn the bucket upside
        down and set the filter into the inverted, bottomless bucket to
        make a stand that holds the filter about 6" off the bottom of the
        sump.  I cut large holes in the bottom of the stand to allow water
        to flow from the filter into the sump.

Sump & water

        The sump is a 14 gal Rubbermaid storage box.  The pump is a Maxijet
        265 gph powerhead.  The pump is just set in the sump and 1/2" 
        flexible tubing attached to the powerhead outlet returns the water 
        to the tank.  The return jet is made from 1/2" pvc elbows.
*note*  The water return is about 1" below the water level in the tank.
        This is important because when the pump is turned off the water
        will siphon back into the sump until the level of the return tube
        is reached.  If the return jet is too deep in the tank, the sump 
        will overflow.
           /    |     \
          |   __|__    |   pvc elbows
  ~~~~~~~~|  |  T  |___|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  clamp   XXXX  A  |   |__
          [  ]  N  |      |  
  flex    [  ]  K   \_____|
  tubing  [  ]


        4'- 3/4 pvc                     $2 (building supply store)
        misc pvc fittings               $2 (building supply)
        3/4" ball valve                 $3 (building supply)
        1'- 1" flexible tubing          $1 (hardware store)
        3'- 1/2" flexible tubing         ? (I had some laying around)
        misc hose clamps                $2 (hardware)
        2 - 5 gal buckets w/lids        $2 (surplus store)
        2x4' eggcrate                   $8 (building supply)
        1x1' 1/4" acrylic                ? (I had some laying around)
        prefilter pad                   $3 (aquarium mail order)
        ~3gal bioballs                  $18 (fish store)
        14 gal sump                     $5 (discount store)
        265 gph pump                    $15 (aquarium mail order)
        AC 200 sponge                   $1 (aquarium mail order)
        aquarium-safe silicone          $2 (building supply)
        pvc cement                      $1 (building supply)
        Total                           $65

        The cost of this filter is more than a UGF or sponge filter with
        a couple good powerheads, but it is still certainly affordable
        biofiltration, and -very- affordable compared to other commercially
        available trickle filters.

        I have had this filter in operation for a couple months with no
        problems.  With the head loss in the water return, the flow is
        somewhere near 200gph, which is filtering the water 4-5 times
        per hour.  
        I cycled the tank using the trickle filter and a sponge
        filter from an established tank.  There have been no detectable
        signs of ammonia or nitrite using Tetra test kits.  

        The bioballs I bought are rated at 40 gal freshwater/gallon.  I
        have about 3 gallons of bioballs, so with a safety factor of 3,
        I dont anticipate any lack of biofiltration, even with bulky
        S. American cichlids.

        The filter does make some noise, especially the water being sucked
        into the inlet.  This may be objectionable to some people, but the 
        noise could probably be reduced considerably.

Up to Plumbing and Filtration <- The Krib This page was last updated 29 October 1998