I have had an issue getting my nitrates to drop below 10ppm. Let me start with my tank information and parameters. I have a e170 that i have added a sump to. Run the hydra 26 hd that came with the tank on a slightly modified setting that BRS came up with to replicate the coral lab. 200-250 par at top of scape 80-120 at sand bed. I have 2 gyres mounted to left and right side of tank, the run a few diff cycles a day They ramp up for 15 min a day enough to move some sand around to keep things from setteling. Have about 3-4x hour turnover frm tank through sump with a curve 5 skimmer and a basket of bio media. Use filter floss in place of sock and change out every 3-4 days. I have converted the ato that came with the red sea sump to a ATS. I dose 38ml of Aquaforest a+b+c+ to keep parameters stable. I also have been dosing 2.5 ml of nopox a day, may be the issue. Parameters are: Salinity 1.0255 Alk 7.9dkh Cal 430 Ammonia and nitrates 0 Nitrate 10-12 Phosphate 0-.02 Magnesium 1450 Ph fluctuates between 8.07-8.25 Temp 77.7-78.0 I cant seem to keep any acros have killed about 6-7 frags over the last 6 months. They seem to be ok for about 2-3 weeks after adding then either rtn overnight or stn over the period of 1-2 weeks. Other sps like montis seem to do fine in my tank colors are jus slight washed out but they grow fairly quick. I have one mili that seems to stay alive in my tank and has even colored up slightly but is not growing and has no pe that I have seen since adding to my system. My ats has never really taken off like some i see but does grow some hair algae and gets some slime on it to. After tons of reading I have come to the theory that my nitrates are to high and phosphates are to low. I went a month doing a 10% water change every 3 days and my nitrates seemed to just jump back up to 10 within 48 hrs. I am considering raising my phosphates to .07-.10 in hopes that my nitrates will be more easily consumed. If I do this should I stop carbon dosing? Should i add nitrifying bacteria when dosing phosphate? Should I continue carbon dosing and dose bacteria at same time? Or is there something else all together I should try?