i don't clean the back of mine, because it's too much of a hassle. also, i figure a little algae on the backside can only help, so why bother with it? there's other creatures as well that like to reside on the back glass, and i don't want to destroy their home either. now i have coralline growing on the glass, and i definately don't want to wipe that away. so, my advice to you, is if you don't have to look through it to see what you're looking at, just leave it be. besides, i like the way the glass looks when it's covered with stuff. there's my .02