Bacteria in a bag, I have used it with good results. It is called greenex. We put it in about 3 months ago and the algae was all gone in a week and is still gone. The neighbors put it in their pond and it worked for them . You can buy it on line at greenex.com for 80 dollars a kilo plus shipping . I put 6 kilos in 3 acre pond, running aereator 24/7. helps. Will not hurt fish, plants, wildlife. Troll
