Doesn't work for me at all
First of all, I have to make it clear, that I purchaged PhosFree in my local store instead of Amazon.This product "PhosFree" totally doesn't work for me. It damaged my DE filter completely, so I have to replace whole set of DE filter grids, spent about $200 to make pump system work."PhosFree" blocked my DE filter when I used it in first time, even I extactly followed the instruction NC provided. When filter was blocked I consulted their customer service, was told that I can try Commercial version of "PhosFree", I trusted them and tried it, but it was even worse. My whole pump system doesn't work at all, whole pool was covered by green algae after 3 days. I called a poolman, he told me that he has other 3 customers have same problem, there is only one way to resolve it, that is to replace whole set of filter grides.I strongly suggest DO NOT use this product "PhosFree" in your swimming pool if you are using a DE filter.