My tank is low also from what I can tell. I use red sea test kits. Zero nitrate, trace of phosphate. I've been using vibrant for about 2 months,with carbon and phosban in reactors reactors but I've still got hair algae. I feed sparingly twice a day. Diatoms and red algae have disappeared.I have a mixed reef and most corals are doing fine. It's a 100 gallon tank with 30 gallon sump.4 inch naso tang,3 blue chromis, 1 firefish, 1 royal gramma,1 canary wrasse. That's why I was asking about feeding corals because I try not to overdo any feeding but hair algae still hangs around, mostly on plugs and rockwork. SB Reef light 32 WiFi on 10 hrs a day at 40% blue,6 hrs a day at 10% white.