On my 150 gallon tank I have two Eheim 2217 canisters and I still see small debris floating around. It is a tank that has been running for about five years and it is never ending. I switched the background of my tank to a light color just to make it less noticeable. The water parameters are good. 10 nitrate, 0 nitrate and ammonia, 7.0ph. I have an auto drip system with about 10 galons per day going into the system. I was wondering if there was a way to put a 50 micron sock in each canister or something. I thought this might help .... maybe Im just too picky. Any thoughts?