I have a 15 aio and my phosphate is steady on 3 with the Salifert text. Doesn't even read on my Hannah. My lfs sold me a small up to 60gal. Bag of Phosguard that I've put under my floss overflow at the bottom gate to the next chamber. I know I don't want to strip the po4 that fast does anyone have any suggestions on how fast this will lower my phosphates? How often should I be testing? And how long is safe to keep in the tank?