I just replaced the filter sponge in the basement drum with a larger, coarser one, which should be better for the plecos. I also switched out the powerhead for a new Tetra Deepwater pump, which is a better fit for the setup: more air, greater tolerance in depth variation. I added a lid to the basement tank to conserve energy. Basement temp normally stays decent, but several days of freezing weather in a row have leached the warmth out of it.