DIY Cannister Filter volume?

sorberj

sorberj

wannabe fish whisperer
Sep 14, 2009
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McCleary, WA
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Jerad
I'm getting ready to try making a DIY cannister filter so that I can go fully planted (I'm on a UGF right now). Any suggestions on the volume/size that the filter should be? I'm on a 55 gal right now but I want to be able to upgrade to 125 gal. I found information on flow rates for the filter, but nothing on how much media/water it should contain.
 
A five gallon bucket should do ya.
 
I was hoping for something a bit smaller since I'd like it to fit under the tank. Are there any rules of thumb for this sort of thing (like the much maligned inch per gallon rule?)
 
Whatever you chose if you plan on having the canister under the aquarium make sure canister container you choose has a good enough and strong enough lid & seal so that water pressure pushing from the inside trying to lift the lid doesn't leak past the seal or deform the lid to do so.

The closer the the water line you place a canister the flimsier you can design it, but once you place it under the water line and especially under the tank, it is a potential water bomb trying to burst 24/7.

I built my own canister which I tested thoroughly and even though I had an O'ring lid becasue it was wasn't strong enough I had to set the canister next to the aquarium where it worked perfectly. Move that same canister to the floor and water pressure would start to bow the lid and push the O-ring off its seal and water would just ran out.

This is why manufactured canisters have clamps of some form and lids are reinforced and the O-rings engage a knife edge to place allot of force on the O-rind to stop water.

I never flooded my house becasue Im en engineer and look for these things even in manufactured canisters. The only DIY housing that cones to mind that would work IMO is an old recycled pressure cooker pot or rug shampooer canister, both of which are designed with high compression lids.
 
Good point on the pressure, I was thinking of using PVC for the main body so that probably means mounting it on the wall closer to the water line, which makes the bucket idea a bit more difficult.
 
Actually PVC would work fine with screw on lid and gasket you could compress. The problem would be having to unscrew it each time and also line up the fittings going through the lid unless the lid was on the bottom.

When it comes to sealing the much smaller holes needed to pass wires or fitting its not a major problem becasue water pressure is being exerted on a much smaller surface area. But the lid usually has much greater surface area so water can exert a much greater force on a lid vs a fitting.

Remember that irregardless you canister will still need to sit below the water line by at least a few inches for the siphon to work properly otherwise the pump will run dry.

Also remember that if you use too strong a pump like my DIY or like the FX5, so that while running it creates negative pressure inside the canister (vacuum), the pump will slowly pull air molecules right out of the water and that air will accumulate slowly displacing the canister with air until the air reaches the impeller and the pump will cavitate.

Why the FX5 (5 gallons) with its 600 GPH pump has to shut itself down every 24 hours to purge all the air its accumulated. MY DIY had a Rio 600 GPH pond pump in only a 1 gallon water container, it would start to empty of water so quickly that I had to put it on a wall timer to shut itself down every 4 hours for 2 minutes at which point it would belch air out the intake tube.

Other then that my DIY worked great. This is why most manufactures use endemic pumps in their canister filters and only the FX5 becasue of its massive pump requires a purge cycle, but what you get in return is massive cleaning for months rather then weeks.
 
1.5 gallons would be plenty for DIY cannister. Eheim 2217 is 6 L, appoximately 1.5 g. From there it just depends on your pump.

If I were doing a DIY cannister for a 125g, I'd go like CWO above and put a 600 gph pump on it, probably with a 2-2.5 g filter volume.....or better yet two filters, each 300-400 gph, 1.5g filter volume.

I'm doing a 120g, 3 filters, between all three the rated/combined pump speed will be approximately 850 gph....after filter material and tubing, I'm hoping for around 500 gph.
 
odinthejd said:
I personally wouldn't use PVC if it was way under the tank becasuse if it did gain to much pressure it would be like a shotgun of plastic and would be quite dangerous and would also be a pain to clean up. If it even gained enough pressure.
Click to expand...


8" PVC, which is too big to use, is rated at like 120 psi burst pressure....never gonna get near that with an aquarium!
 
Here's what I'm thinking....I left the dimensions out and nothing is to scale. I was going to mount the pump (not shown) externally on top of the canister. Chamber 3 would be attached directly to the lid with the other two chambers either latched or screwed on to the previous chamber (depends on what I can find at Lowes or Home Depot). Chamber 1 would be mechanical, since it's the easiest to clean 2 and 3 would be biological , but I wanted to leave the option of using chemical, hence the three chambers.

FilterDesign.gif


Any beyond all of the questions I've asked so far, any more suggestions?
 
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