Toothbrush, wind and yank, watch it doesn't clog your downflow teeth; but to do the most good, a GFO reactor (about 50.00) with a load of medium changed monthly until you see the algae thin out and finally die out. THe problem is phosphate, which leaches out of rock and sand (and tap water) and until you've exported it from the tank (eaters only poo it back in) you'll be seeing the green. If I dropped a rock with it into my tank, it would lose its algae within a week...nothing eating it, just not that much phosphate for it to use.