For the past two and a half weeks my phosphates have been around 1 ppms. The funny thing is I don't have any algae in my DT. My refugium is getting a real dark red to black looking algae inside there with bubbles. My calcium is around 490 and mag is around 1500. I have not performed any water changes since my tank started but did come home to 3 approximately 20 gallon floods. Ammonia, Nitrite is 0 ppm and nitrate is around 5. Also weird is my calcium and mag has jumped and lowered during this 2 week span and I haven't dosed anything. I know this is weird and only things like this happen to me. What am I to do. All fish are looking happy.