Subject: Blue-green algae I do not believe that blue-green alg > well in oxygenated water. On the other hand, I can't explain why > often thrives attached to the outflow ledges of many AquaClears The worst cyanobacteria infestation I've ever had was on the waterfall of my paludarium. You can't get much better oxygenated than that!<g> Karen Randall Aquatic Gardeners Assoc. Boston, MA