NO3 will not fall below 10ppm

IanMauger · Jan 8, 2018

Now I’m not that concerned because I’m not seeing much if any ill effects, but I’m more or less curious as to why this is going on. Not sure what the issue is, but my NO3 will not fall below 10ppm.

For what it’s worth, I had a NO3 issue where they were up to 40ppm. I began Carbon dosing via NOPOX which did bring them down to 10ppm, this took months. I have since discountinued NOPOX because the added headache of bacteria film maintenance. Since discontinuing 6 weeks ago I have not had an increase in NO3.

My parameters are:
9.5dKH
420-440ppm CA
1300-1355ppm MG
10ppm NO3
0.05ppm PO4

My export methods are medium to wet skim (skimmate is darker tea colored), fuge with chaeto (needs trimming monthly), ATS (began 3 weeks ago (has initial growth, green/brown/slime algae), a liter of Matrix in fuge. Now I can see on the matrix and rock in the fuge micro bubbles which I guess is N2 offgassing from anaerobic bacteria.

I have little algae in the main display and what ever I have is quickly taken care off by the tangs, mower blenny, and CUC. My sandbed is turned over by the watchman goby and snails.

Any ideas??

Randy Holmes-Farley · Jan 9, 2018

If you are no longer using NOPOX, and nitrate is stable at 10 ppm, that sounds fine. If you were still dosing and wanted it a bit lower, I'd dose a bit more than you were before.

There are lots of things that limit the extent of the various processes, such as organics being needed for denitrification, trace elements (such as iron) being needed for algae growth on an ATS. These sorts of things may be limiting the processes and aren't allowing nitrate to go much lower, relative to the daily input of ammonia from food metabolism.

IanMauger · Jan 9, 2018

Randy Holmes-Farley said:
If you are no longer using NOPOX, and nitrate is stable at 10 ppm, that sounds fine. If you were still dosing and wanted it a bit lower, I'd dose a bit more than you were before.

There are lots of things that limit the extent of the various processes, such as organics being needed for denitrification, trace elements (such as iron) being needed for algae growth on an ATS. These sorts of things may be limiting the processes and aren't allowing nitrate to go much lower, relative to the daily input of ammonia from food metabolism.

Thank you Randy! I think I jumped on the ULNs bandwagon because it seems we are bombarded with everyone trying to drive down nutrient numbers to the bare minimums.

Personally, I think I was more or less obsessed with chasing numbers rather than looking and studying my tank. I am expeierencing excellent growth in everything (softies, LPS, and SPS). Coloring has become much more vivid after I slowly dropped and cut off the Carbon dosing and down adjusted my Kessil’s intensity.

All that said, even at 10ppm NO3 I don’t think it’s much of an issue.