Nitrate and Phosphate in Reef Tanks

Reef tanks are not sterile — corals need some nitrate and phosphate. Many keepers aim for nitrate roughly 1 to 10 ppm and phosphate around 0.03 to 0.1 ppm, adjusting for coral type and algae pressure. Zero nitrate with starving-looking SPS may mean too aggressive export.

Heavy feeding, large fish, and skipping water changes push both up. GFO, skimmers, and refugiums export nutrients but can strip too much if misapplied.

Test weekly and log results. ReefDiary charts help you connect a new feeding routine to a phosphate spike two weeks later — easier to fix when the timeline is visible.