Although a little drastic, I highly recommend Paul Kromholtz's bleach treatment. Many, many if not most plants recover quickly and as Paul says, the algae is gone. Until I found SAEs two years ago, I used it to get rid of red alga (much easier than the copper treatment). When Paul says 5%, he means 1 part bleach to 19 parts of water. The terminology can be a bit confusing because household bleach is labeled as 5% Sodium Hypochlorite! --Neil