How big is the tank you're using, and what kind of substrate do you have? It might be possible to run a reverse-flow undergravel filter along with a power filter. The way this works is, using a reverse-flow adapter on a powerhead, the water is forced down the lift tubes for the undergravel filter and up through the gravel. This will blow any waste in the gravel up into the water column, where it can be removed and filtered out by another filter (like a hang-on-back power filter). The end result is that your gravel stays much, much cleaner and therefore the need to clean the bottom of the tank is drastically reduced.
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