If you have a major problem with your phosphates (>2,000) then do not waste your time with any other product but this. I used the Phosfree and Phosfree Commercial products and they did not put a dent in the phosphate problem. This product brought down the Phosphate count from 4,700 to 400 with two treatments. I will only buy this product going forward. Make sure it is the Phosfree Max in the box!