I was using a cheap powerhead for two stacked 75 gallon sponge filters (on top of the hob filter; it isn't the only thing running.) It stopped working a week ago, so I'm on the search for a new one. Using air pump in it right now, but I really want the extra water circulation. I'm not having much luck in searches; any suggestions on a power head or wave circulation thing, or.... Whatever name they wanna call it, for a 55 gallon mbuna tank? At least a few hundred gallons per hour circulation; the one I bought didn't have a rating anywhere. It isn't a big rush, because I'm using the air pump and these were companions to the HOB anyway. (Also about to free my holding tank for Jerkface, so I can move his HOB filter over.) So really really no rush. I have time to be picky with finding a good one, and time to save up to get it.