I have a 29 reef tank that has been setup for about 6 months i have 40lbs LR 30lbs LS, PS and a fluval 404 just for water movement which gets cleaned once a week. All my levels in my tank are fine, Amonia o, rite 0, rate 0 just the phosphate is high. now ive been sphoing the sandf lightly to clean jsut suck up the algea to remove it but it jsut comes back. also im doing 5 gallon water change a week. I use Ro/DI water too i dont no what the problem is help me plz