So this problem has been plaguing me since I got my tank in july. My 55 was given to me from a buddy who's grandmother had past away. When I picked up the tank it was disgusting! Dark green to black alge all over everything! Well after hours of scrubing I got it clean. The only thing I've been fighting with is the hard water stains on the back of the tank. I've used windex and hot soapy water with a green scrubby. Does anyone know how to or a product to use to get rid of hard water stains?