I have a 29 gall freshwater tank that has 6 black skirted tetras, 6 panda cory cats, and a rubber lip plecostomus. I purchased my pleco 1.5 years ago and "he" has been doing great. I feed him a wafer once a week. I got a new tank about 5 months ago and he will not clean the back glass wall. It is building up with green alge. The other 3 walls are in great shape. With the new larger tank I did have to upgrade my filter and I am worried it is possibly causing too much turbulence for him. I cant turn it down any further. He is always stuck to the back wall hiding during the day though. What do you think?