OK, I can live with that option... I am getting resigned to tearing it down and pulling out the Flourite- I don't want this junk just blasted out the top. I have a "fishbowl" I can put the plants in- they seem to be doing well, and it would be a shame to waste them... However, in the interest of being "balanced", which powerheads are reversible? I'd like to have a pair, as I'm just thinking that a single unit will have a decreasing range of effectiveness as I move further away- even in a 20 gal. tank.