sludge

Good day. I have this brown stuff- algae? Debris? on most of my plants and inside my canister filter and tubing. Help! What is it and what can I do about it? I have .... 20 gallon long tank with penn plax 500 canister filter with foam and sponge filter media. this week added fluval prefilter...

I have over the back hanging filters for my two 2 gallon aquariums. Sometimes a little sludge gets stuck on the plastic that the filter cartridge sits in. I normally clean this off in the sink. Not back into the tank.I received two conflicting answers from the same Pet Store Chain, but from two...