I appreciate the fact this is a thread about canister filter, but was curious to know of you had concurred maybe an internal floating bed filter?
They are extremely cheap to build and you can run multiply tanks off one large air-pump. They are also really good filters that really help the water quality.
There are two designs you can choice from. One which uses an old 1 litre coke bottle turned upside down. With some wholes drilled at top and bottom an air line/ airdrome optional and some k1 filter media.
The other is the same only incorporates a elbow and a piece of pipe with more wholes or slots drilled and a sponge. Look up homemade bed filter and homemade floating bed filters on you tube. I've made 3 and it cost me a fiver.
Heres a pic of mine I made. Only I managed to find so spare parts in a bargin bucket at my lfs
that cost me £2 I just gotta put an old price of media sponge inside the grey inlet strainer. Hope you like it?