Bleach works fine but h20 don't do shit....... I've battled for a while with algea until I tried algea eater. Ever since used that stuff I never had to worry about algeas. And what's nice about it is that you can get it from walmart in the fish/aquarium section. Its about 5 or 6 dollars total. Its the best thing I've used asides from brewing my own beneficial microbe tea.