I have no idea if this product actually works, as I purchased it based on the fact the description stated it treats up to 8000 gallons. However, the instructions on the bottle state to use 20 oz. for the intial treatment for an 8000 gallon pond and 10 oz for an additional application after 2 weeks. The bottle is only 8 oz. According to the instructions on the bottle, 8 oz. will only treat 1100 gallons, not the 8000 advertised.Shame on Amazon for selling a product with such fraudelent claims!