I have a 20 gallon high with an undergravel filter and a powerhead and the powerhead is sucking all kinds of crap through and recirculating it in the water. I know this is bad for the health of the fish and looks bad too. Any ideas why this is happening or how to fix my problem?

Hi Tex,

IMO, get rid of the undergravel filter and use a cannister filter or employ a sump. UG filters are archaic and IMO only postpone the inevitable.

Large gravel granule size? Perhaps get some gravel that will compact some more and catch that stuff...
Also, is your tank on a stand with a light underneath it, shining up into the bottom of the tank by any chance?

I think it is churning up poop but it could be some algae because there was algae starting to grow on the gravel. The stuff the powerhead was spitting out was white in color and was really little but my thought was that the bacteria might have started digesting the poop making it look that way or that the impeller in the powerhead had something to do with it. There is no sun hitting the tank but i do have some java fern in the tank.

Thats strange...perhaps cut back on feeding to let things get digested in there..

ok, I'll give that a try and see how it goes. thanks for all your help.