Treatment system for larger ponds. The 6in. disposable/recyclable plastic sphere is preloaded with a natural bacteria and enzyme blend, designed to treat the real problem of ponds and lakes: excess nutrients. Patented time-release system meters daily doses of bacteria and enzymes that help keep sludge and algae blooms in check. Safe for humans, pets, fish and plants. U.S.A. Treats 1/4 acre (about 250,000-gallons) Treats water for up to 30 days Model 10199