Well, just when I thought I had my green algae handled, i looked closely and there were thousands of little spots growing ALL.over the acrylic. This stuff is hard to scrub. So i grabbed my algae scrubber and got after it. I have trumpet snails, mostly tiny babies. Well I normally knock them all off before I use the scrubber, but im sure you can guess this time I missed one and he found himself in between my scrubber and the tank wall. I noticed after it was too late. He of course was smashed, but much worse, is the fact that his shell caused 3 enormous, deep, noticeable scrapes right on the front of the tank. Makes me want a new tank.