API test kit? If so then I would double check with a more reliable kit for sure. Also how long has the tank been running and were you using live rock or dry rock? Sorry for all the questions but it can help us figure out where you are with your tank.
So for the really late reply my tank is 8 months ago old I have around 30 pounds of live rock I have 40 ponds of live sand and my lighting is a 75 watt mars aqua full spectrum led.
ive never had problems with apI testing kits if you o it exactly as it says. 16 years ive been using api. steer clear of redsea