# linking canister filters



## bigeflashgordon (Aug 6, 2013)

I've been wondering... is it better to get two smaller canister filters or one large canister? I've been thinking of linking two smaller filters together and splitting the outlets on opposite ends of the tank with one center inlet pipe.. Is this a horrible idea? Should I keep them separated or scrap the idea and get a larger single canister with 2 outlets? It'll go on a 65 gal heavily planted tank build I'll be starting soon


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## TAB (Feb 7, 2009)

its better to keep them seprate. 2 main reasons for this. 1 easy of cleaning. 2 they won't fight each other for water.


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## niko (Jan 28, 2004)

Main problem with canisters is the Oxygen. It gets used up very fast inside the chamber. So if you link them the microorganisms in the first canister will leave no Oxygen for the organisms in the second canister.

The basics of biofiltration are simple: The water needs to move SLOWLY through a SHALLOW bed of biomedia. That says one thing - all commercially available canisters are a joke. Is that entirely true? Mostly "Yes" and a little "no". Most often you can run the tank without a filter. Most people don't even know why they use certain biomedia. The flow through the canister is usually bad (plugging and channeling). A tank without a filter at all is definitely at higher risk of going bad but that's because most folk don't know the first thing about running a tank AND refuse to use common sense.


Get the biggest canister filter you can afford. Fill it with pumice (bonsai ebay stores have it). 0.5-1.0 cm size of the grain. That is your bio AND mechanical filtration at one. It needs to be rinsed in tank water as needed (depending on how crazy you get about the number of fish and the food). That's it.


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## bigeflashgordon (Aug 6, 2013)

I'm purchasing a drilled 65 gallon tank that has 2 outlets but no overflow box inside attached to the tank.. I'm from the reef mind set of very organic and let the tank establish itself slowly and use the biological filtration to maintain a balance.. I try to apply the same methods to my current planted tank and have done well, but I'd like to step it up a big.. I'm considering a canister with the new set up, but since it is drilled I'm also leaning towards building a sump.. Of course with any co2 injection you run the risk of co2 dissipation through water agitation.. But I'd like to think that running a sump outweighs the cons.. Would a sump set up and an inline co2 atomizer do a decent job with proper diffusion? Also if I had a sump I could pack it with biological filtration options and let it establish over time.. Would anyone do this? Or should I go with a canister and keep it a closes system?


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## JG06 (Nov 5, 2006)

I like canister filters because all things equal, if the motor fails or loses power, you most likely will not end up with water on the floor.

There are better designs out there (wet/dry trickle, sump type, etc.) but canister filters work and they're relatively foolproof.


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## bigeflashgordon (Aug 6, 2013)

Another question... Is one large canister better than 2 good size canisters? Id assume that two smaller ones would get better overall flow and you can eliminate both corner dead spots with the inlets.. It seems more cost effective in my position than scraping my good size filter for a single large one.. What do y'all think?


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## niko (Jan 28, 2004)

Yes, two are better than one. The reason being that what you want from biofiltration is to be shallow and very large area. That means a short and very wide filter (like a pan) and the water running on top. Imagine a shallow creek with a gravel bottom - that is the ideal biomedia setup in Nature. The water needs to flow pretty slow, but not too slow either. You do not get any of that in any canister filter. So if you use two of them the idea is that you will be closer to the ideal biomedia setup as described above.

All of this is theory but you will not find a better explanation anywhere else. Read Yo-Han's posts about what exactly biofiltration is so you understand that it is very far from being only about Ammonia and Nitrate like everybody thinks.


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