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victory in aquarium filtration

the journal of Michael Werneburg

twenty-eight years and a million words

I have two aquariums in the house, each with a canister filter from Tetra, as pictured below. I've been tinkering with the formula of filter media, but I've noticed that crud keeps winding up on top of the various filter trays. I couldn't work out what was happening.

That changed when I read a seven-year-old comment on a Youtube video. The commenter explained that there is often a gap between the filter media trays and outer shell of the canister. This, though only a millimeter or so, allows water to go around the filter media rather than being filtered. I did as she/he suggested and wrapped each filter tray in microfiber fabric to force the water through the filtering media.

The result has been astounding. While the aquarium can get quite messy at feeding time, it is soon so clear it's like the fish are swimming in air. So effective, so cheap .. and yet I wonder why the canister manufacturers allow the water to bypass the filter trays like this.

These are the canisters.