It was an infestation of Oedogonium, a particularly nasty hair algae, that finally prompted me to develop the 5% liquid bleach treatment, which got rid of it. Before that, I tried putting a gallon jar with Oedogonium in total darkness for six months. At the end of that period, the algae was still alive, and it resumed growing as soon as it was returned to light. Paul Krombholz Tougaloo College, Tougaloo, MS 39174