High Trates low Phates?

Davy Jones · Nov 22, 2016

The tank just seemed off last night so i did some testing. All my numbers are off other than alk (only one i test regularly) SG 1.027, cal 500ppm, alk 7.9dkh, mag 1600, Nitrates ~30ppm, phosphates 0.

Although i am concerned about everything and have taken steps to remedy the cal and mag, i am confused about the nitrates and phosphates.

I Have 0 algae in the tank other than what grows on the glass and any coral skeleton showing. Both are a brown in color.

At one point in time i had some tufts of bryopsis, they are now gone completely at no action by me.

About this same time i noticed some burnt tips on my sps and the alk was up to about 9dkh so i lowered my dosing. Since then i have had very little growth out of most of my sps.

I do not run GFO, biopellets, carbon dosing, gac or a fuge. Just a skimmer, filtersocks (that get neglected from time to time) and waterchanges of around 10 gallons a week in a 65 gallon system (2 weeks behind in that currently) and about 1 litre of Matrix that is scattered throughout my sump which has only been there about a month.

Why would phos drop to 0? I feed 1 cube of mysis a night. have 7 fish. some nems, euphillia, rics, and the like.

Now i dont plan on doing anything drastic but i want my numbers where they should be since things arent looking great in the sps department.

Last night i dosed 6ml Nopox (about 3/4 what was recommended by their chart) added the other litre of matrix scattered throughout the sump again, set my skimmer to wet since it hasnt been skimming much lately and plan to do a ~10 gallon waterchange tonight.

I also removed my esv 2 part and replaced it with red sea reef foundation elements so i can just dose ALK and let mag and cal fall to normal levels.

I guess what i am asking is this: Why would phosphates read 0 when nitrates are high, and am i on the right track to lowering them? (i dont want to shock anything by removing them too fast)

Randy Holmes-Farley · Nov 22, 2016

Nitrate does not cause algae. It needs many things at the same time, including a source of phosphate. If phosphate is very low, you may not get algae.

There's no inherent reason these need to tack together since many of the export methods are somewhat independent. Also, the kits may not be accurate, either or both. lol

NOPOX or other carbon dosing scheme is a fine way to go, although if phosphate is really VERY low, nitrate may not drop any further since the bacteria need some.

Davy Jones · Nov 22, 2016

Randy Holmes-Farley said:
Nitrate does not cause algae. It needs many things at the same time, including a source of phosphate. If phosphate is very low, you may not get algae.

There's no inherent reason these need to tack together since many of the export methods are somewhat independent. Also, the kits may not be accurate, either or both. lol

NOPOX or other carbon dosing scheme is a fine way to go, although if phosphate is really VERY low, nitrate may not drop any further since the bacteria need some.

Good to know. I thought that you wanted to keep them within a certain ratio? Redfields or something like that for best health of your coral. Should i be dosing trace amounts of phosphate somehow?

Codym808 · Nov 22, 2016

I was having the same problem with nitrates and phosphates, your alk and cal is a different issue which you said you are addressing.

I was having 20ppm nitrates (via Red Sea) and 0ppm phosphates (via salifert) with heavy feedings for fish and coral. I could not get my nitrates to go down until I started dosing brightwell neo-phos last week. In about a weeks time, I'm getting readings of 10-15ppm nitrates and 0.01 ppm phosphates. I think in a month I'll get my numbers down to where I'd be more comfortable with.

Davy Jones · Nov 22, 2016

Codym808 said:
I was having the same problem with nitrates and phosphates, your alk and cal is a different issue which you said you are addressing.

I was having 20ppm nitrates (via Red Sea) and 0ppm phosphates (via salifert) with heavy feedings for fish and coral. I could not get my nitrates to go down until I started dosing brightwell neo-phos last week. In about a weeks time, I'm getting readings of 10-15ppm nitrates and 0.01 ppm phosphates. I think in a month I'll get my numbers down to where I'd be more comfortable with.

Yeup, cal and mag are from blanket dosing of 2 part isntead of testing weekly i just tested alk and let the rest go.

Ideally id like to get my nitrates to between 2 and 3 somewhere and phos around the .02 mark or something there abouts.

Thanks for the experience with Neo-phos. Might have to try some if waterchanges, skimming and nopox doesnt work.

Randy Holmes-Farley · Nov 22, 2016

Dirtrider225 said:
Good to know. I thought that you wanted to keep them within a certain ratio? Redfields or something like that for best health of your coral. Should i be dosing trace amounts of phosphate somehow?

No, you want them both in particular ranges, not in a particular ratio. For example, just because phosphate is 1 ppm or 0.0001 ppm doesn't imply the optimal nitrate level is some huge number or some vanishingly small number.