I had this problem also. Things to know you have to many nutrients in ur tank. Do you have a skimmer if not its prolly best to get one. If you do run in just a slighty wet so the extra food will hurry up and get out of your system. Dry will take it a little longer. Use rodi
water. Water straight from the sink can have extra nutrition in it. You can sometime buy it at a lfs
reactor will help bulf reef supply has a dual reactor with carbon and gro chambers for around 75 bucks. Do 3 days with no light if you have coral it will be fine. If any coral dies then they were on the verge of death prolly do to the water quality of the high nutrients causing other problems to ur parameters. Feed every other day or every 2 days. This could be the root of ur problem I just found this out also. I fed twice a day everyday and I was told u only need to feed every other day. This helps. Trying to do as many things at once seemed to do the trick. Atleast what you can. Bc idk what u have and what u dont have. The cynao is most likely consuming all of ur phosphates so if it says there in check thats why. Ur getting false readings. Keep an eye on the nitrates as well. More than likely its going to be to much food to often not rinsing food with rodi
then drainifn the food before serving it. Or not using an rodi
maybe needs new filters if u have one. Do u think ur tank could be over stocked?