Low nitrate high phosphate problem.

sterlingbejma · Jun 16, 2026

I have a question I need some answers too. My nitrate is now 1.8 and my phosphate is .26. My problem started with my phosphates were at .21 and my nitrates were around 8.4. I started doing water changes and siphoning a quarter of my sand bed of my aquarium cause I thought maybe the sand was harboring the phosphate. I was doing this once a week until I siphoned the full sand bed in the aquarium which would take a month. I was only doing a 10% water change with each time. I noticed some of my flesh bands on my Ophelia were retracting and the polyp extension wasn't what it should be so I did a water test and noticed I probably stressed my corals by dropping the nitrate so low. But now my phosphate is still at .26. I just added some gfo to my to my reactor 1/3 the recommended amount so I don't stress out to corals further by dropping my phosphate. I also turned off my skimmer in the time being. Is there anything else anyone could think of that I could raise my nitrates back to where they should be to save my corals. Thank you!

Randy Holmes-Farley · Jun 16, 2026

The phosphate is fine and is within my recommended target range. If you want to bring up N, you can feed more or dose some form of N, such as ammonium bicarbonate, sodium nitrate, or calcium nitrate.