Algea!...
 

I have algea that wont scrape off the glass. Any suggestions?

Little green dots?

It can come off, but does take some elbow greese. If your tank is glass (and not acrylic) you can use a razor blade ... just don't go anywhere near the edges.

Agree. And there is a simple way to keep this from ever returning. Each week during the water change, just clean the inside of the glass with one of those sponge-type scrapers whether it appears to need it or not. This catches the very beginnings of any algae, when it is invisible to us, so it never has the opportunity to increase.

Byron.