grows quick

Tank is 10 years old PO .09ppm always runs high NO3 0 NO3 2ppb Light 8 hours per day Tried :reef flux, algaefix, time waste away, UV unit, 7 day blabk outs. Corals snow with MB7. I tried no water changes for three weeks and then water changes every week. No luck. When I scrub it away. It's...