Mobile Bay Reef Keepers

I tested the water from my R/O unit and I think there are phosphates in the it. (.5 ppm at most) The membranes are only about 4 mos old. Is the R/O unit supposed to remove all the phosphates from the water? I am seeing a small amount of hair algea growing on some porites and I'm trying to figure out where the excess nutrients are coming from. I didn't know if such a small amount of phosphate could contribute.

.5 can easily contribute to the hair algae you are experiencing. What kind of unit are you using? I would contact the manufacture and get all new cartridges and a new membrane.

My water has 1.0 phosphates and after about 4-6 months the filters get such a build up that they start releasing it into my top off water. I have to change the filters often to stop the leaching.