Whats the difference between a canister filter and a hang off the back filter?? What makes a canister filter better?? I currently have a fluval aqua clear 70 hob. Thinking of changing to a canister filter if its better, what brand should I get for my 35 gallon hexagon tank. Thanks.
I can only give you my experience, I started with a bio-wheel, decided I needed more filtration got an Aquaclear.
I was still dissatisfied with the results. I had extremely high nitrates which even WC didn't bring down. I couldn't find the reason for the High nitrates, Decided that the filters needed cleaning. The output edge of both filters had a thick layer of a brown slimy substance which I took to be poop. That told me that the HOB's were not doing their job. As an aside I had started to do a fishless cycle with fish food. Switched to feeding pure ammonia for the cycle. Made a mistake in calculating the amount of ammonia needed and almost killed all the live plants as a consequence. A side issue was that cleaning the filters ended up with a surplus of water everywhere since the AC needed to be primed to get the flow going which added to the water surplus. Have you ever tried to hit an opening about 1" square with water from a full one gallon jug at shoulder height?
The brown slimy stuff told me the HOB's were not doing the job. Researching the problem sold me on a canister filter. I was a bit afraid of the first time priming procedure before I bought the Fluval 206 for a 29G tank because it had separate baskets for each type of media. That turned out to be a misjudgement since I now only run mechanical and bio media in the filter. Also I liked the autovalve design (turning off input and output at the same time) of the hose connections.
Well to make a short story even longer I didn't have a problem with the priming a all just followed the instructions. I started with weekly cleanings as I did WC. Have since progressed or backslid to 3 months before cleaning the filter with weekly or biweekly WC. Cleaning the filter is a breeze, shut the Autovalve off. Open the top snaps take the top of the filter off and move the container to the bathroom, spill out the water. then do a no-no, rinse the sponges in tap water, rinse the container in the tub, reassemble the media trays and the prefilter. Put the container (empty) in the cabinet, reconnect the hoses, open the Autovalve, wait 'til the container fills, plug it back in. There is some tiny air bubbles in the output for several seconds and viola it is running again. No priming, no noise even no water noise. The media consists of the black sponge Fluval calls a biosponge, Fluval Biomax , and a fine felt filter media. I watch the intake tube and clean it when the screen seems to be dirty. the output doesn't seem to need any cleaning between filter cleanings.
This has turned out to be an essay rather than a simple recommendation, but if you need anymore info just ask.