Originally Posted by Jonty
I can do much about the overflow. It's plastic stuck onto the glass, but has slits vertically on the top and bottom. I'm scooping the red stuff off with the net. Any other ideas?
I would completely close off the bottom and let the water skim off through top slits. The same thing that is going on in your protein skimmer is happening in your tank. The only difference is that you aren't removing it, and it just keeps building up.