Hi everyone, I have a new tank that has been running for 3 months. Only 4 fish and 5 corals in a Red Sea XL300. I was using RedSea AB food every other day in a small dose and also dose phytoplankton at night. My phosphates went very high at .52 on my Hanna checker. I stopped the coral food and phytoplankton for a week and did my normal 15% water change. My phosphate is now 0. I ran the test several times. I siphoned the substrate pretty good but why the rapid drop? I know it's not good for my inverts. I had a very mild stage of diatoms when the level was elevated.