Hmmm, running Rowaphos in a phosban reactor made by TwoLittleFishies. It's for my 29g prop tank with a 15g sump. I've been running the media for about 1.5 month and then change. Rowaphos is known to be pretty good. They will not release back phosphate into the tank as some media will. My phosphate is undetectable by the Hagen and the Salifert test kit. I haven't used some lower range test kit, but I am pretty sure my phosphate is pretty low. For that tank, I only feed frozen cyclopeeze once a week. Not much for phosphate to build up.