Test results on your water...
Phosphate? - If you are getting a reading then you have too much in your system.
What kind of source water are you using? RO
How old are the bulbs you have on your tank? What kind of bulbs are they?
When you say you "clean" you water every 4 days what do you mean by this? What kind of filtration do you have on the tank? How many fish do you have in the tank? How much Live Rock do you have? Crushed coral or Sand for substrate?
Give us a little more information about your system so we can help point you in the right direction.
Welcome to AA!