Greenish Algae covering glass..

[Shipley18]

any ideas as to what it is is hard to scrub off, and keeps coming back despite water changes, it must be somethign in my water because i do just use tap water because i can't afford the pure water as of yet!, but its never appeared before and I've always used tap water

 

[1979camaro]

probably just normal algae growth. if you get a magnetic scrubber and run that over the tank every couple days it should prevent the really hard stuff from forming