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  1. #1
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    DIY FBF/tower filter

    Hi all thought I'd put up a quick DIY on some of my ugly but very effective filters.

    These filters are strictly BIOLOGICAL filtration only, so please keep that in mind if your thinking of adding one to your tank.

    heres what you need to get started.

    1x 90mm PVC drain water pipe (length dependent on your tank height)
    1x 90mm drain water pvc T
    1x 90mm endcap
    1x 90mm-40mm stepped reducer
    1m 40mm PVC low preassure pipe
    1x 15mm high preassure PVC pipe(same length as your 90mm)
    1x 15mm high preassure T
    1x15mm high preassure 90 degree elbow
    1x 15mm faucet adapter with male thread
    1x 15mm ball valve
    1x 19mm barb to 15mm male thread irrigation fitting.
    acetone
    cordless drill with 5mm bit
    hacksaw
    teflon tape
    PVC glue
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  2. #2
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    next up take the 40 mm pipe the 90-40 reducer and the 90mm T and assemble as shown
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  3. #3
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    take the assembled body to the tank and size it up just to make sure everything is at the right height.

    then its time to start the water inlet pipe.
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  4. #4
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    drill holes in the side of the T to allow water to flow better into the filter
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  5. #5
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    If your using a pump with adjustable flow controle you can leave out the ball valve saving you $5 and just use the barb onto a female faucet adapter.

    either way you'll need a little 15mm pvc to join the manifold to the 90 degree 15mm elbow with joins to the pipe that runs to the base of the filter.
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  6. #6
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    now for the media, the idea is to attain a fluid state of substrate in the filter so ideally you'll fill the filter to 1/2 way with sand and allow it to rise to 2/3-3/4 up the column when "fluidised".

    if your running a high flow pump a heavier media is better so as you dont get sand entering the tank. pool filter sand works well here.

    as the principle behind this type of filter is slow flow massive surface area a finner sand like silver sand will give more biological activity but to use this sand you need a slower flow rate.
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  7. #7
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    put a few handfulls of nice corse media at the base of the filter like big ceramic rings, then add you sand, if you use poolfilter sand wash it first silver sand is clean from the packet.

    fil the filter to 1/2 way then turn on the pump adjust the flow so as no sand leaves the filter
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  8. #8
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    these filter have excellent biological capacity, 2L of sand is plenty to filter your moderately over stocked tank, as the sand bumps into each other it self cleans itself and you'll often see a mulm develop on the surface that is easily removeed with a small siphon.

    These filters do have their problems, they have no mech filtration at all so need pumps with good prefilters, failure to do this results in muck getting trapped in the sand bed and eventually leads to ph crashes as the muck rots and turns to nitric acid.


    eventually you will have to remove all the sand and give it a good clean in tank water, mine lasted a good 6 months before i had to do this. cleaning the sand is a pain you might be better off just replacing 3/4's of it.


    Also after a power cut the sand can settle and compact, this is less of a prob with pool filter sand. when the power comes back the pumps can fail to have the preassure to re fluidise the sand bed, fitting a 15mm non return valve would help fix this problem.

    I've since modified all my pvc FBF's to now be matrix tower filters. It allows me longer intervals between cleans and i dont have to worry about the sand bed compacting, they dont have the same biological capacity but for a total build cost of under $30 they're a cheep reliable canister filter. the best thing about the design is you can hook it up to anything as seen below i've got it hooked up to an eheim univerdsal 1200l/h pump using a dead 2017 as a prefilter (corse sponges and ceramic noodles).
    Attached Thumbnails Attached Thumbnails dscf4008.jpg   dscf4011.jpg  

  9. #9
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    you can also make these things as big as you like my biggest is a 2m tall unit hooked up to my 6x2x2 running on 8L of matrix.

    Water is pumped via an eheim compact 1000 up about 30cm of 16/22mm hose then into 15mm pvc pipe down to the bottom of the filter, here it rises up through 8L of matrix before cascading back into the tank, the flow rate is low only 650L/h, so it turns the tank over once an hour, this filter has reduced nitrate in my system from ~40ppm to below 20ppm.

    the tank gets top ups once a week to replace water from evaporation and a proper clean and 50% change every 6-8 weeks.



    an eheim pro 3 2080 is also running on the tank and its densly planted

  10. #10
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    A monster filter

    Not so easy to clean?

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