see, I have never been one to have luck with any kind of "quick" phosphate remover, locks, sponges, NONE of that crap, and to me its just that. There is a LFS I go to up here that doesnt sell chemipure, the lady says stopped selling it 9 years ago....blah blah blah..... I love this stuff, and the improved ELITE is some really really good stuff. When I started getting brown, I switched my R/O source, and did 2 5 gallon changes in a week on my 29g cube....