Nitrate- cannot get it to fall

[CHSUB]

Ratios are a funny thing, I find them completely useless. In nearly all cases hobbyist are using hobby testing which are very inaccurate. If the nutrients are there the algae will consume them. Maybe in the ocean certain species over centuries will gain an advantage, however in a puddle of a reef tank over a couple of years or months?

What would the ratio gurus think of this ratio?

 

[Randy Holmes-Farley Verified Community Expert]

What would the ratio gurus think of this ratio?

I think nutrient ratios as reefing targets are basically an inappropriate waste of math.

I have never seen any reason to not just look at the individual absolute values to assess suitability.

In this case, the nitrate may be fine if there are other sources of N, and not fine if there are not. Since you know from experience with this particular tank that it works, then I expect there are adequate other sources of N. For folks who do not have that same experience with their particular system, I'd want to see nitrate higher.

The phosphate is OK. I'd prefer it a bit higher, but its not what I'd call too low.

 

[EnterName]

now the chaos is perfect:

We have Opinion A saying nutrient ratios matter, even in tanks with higher nutrient levels.

Then we have Opinion B saying nutrient ratios matter more when absolute values are low like in nature but less when they are a bit higher like in most reef tanks.

And now there is Opinion C saying they don't matter and absolute values are the most appropriate measure

I love it

 

[JonasRoman]

I think BOTH ratio and absolut values matter. Ofcourse I say, as N and P are the conductor of our tank, if I exaggerating a bit. The ratio in this example is approx 3.8, so very low, meaning its risk of N deficiency for the zooxanthelle/coral. The absolut value are fine I think.
Reason why ratio matters is that it tells me what will be limiting with further decrease, and here it will be the N. Also it tells me that when coral has used what it need for N there will be a waste of P, that maybe isnt ideal (but must not be bad). I would not lower P but rather have an eye on N and try to increase nitrogen input in that case.
Absolute values also matters, as in very hogh values, those can itslef be bad, where for instande very high no3 may be bad for the coral. Very high Po4 may inhibit calcification, etc.
So for me its both.

Jonas

 

[Randy Holmes-Farley Verified Community Expert]

The absolut value are fine I think.
Reason why ratio matters is that it tells me what will be limiting with further decrease, and here it will be the N.

I don't deny that possible value if one wants to know that. It's not trivial to use, however, since one would need to know in what ratio the values will decline.

 

[Dan_P]

I'm not sure I understood you correctly. Delbeek said a 50:1 N:P ratio worked for tanks? That sounds reasonable I suppose. Unfortunately we can't use the study to check it.

The study tested ratios of 117:1 and 211:1 (both bleached), as well as 22:1 and 1:60, which remained healthy. So nothing is really close enough to 50:1 to give us something to work with here .

We also can't tell the absolute P levels just from the ratio. So if the paper's assumption is correct that ratios don't really matter above 0.03ppm PO₄, we wouldn't be able to apply its findings anyway.

I think the following makes clear why I believe the paper correctly assumes that ratios don't matter too much above a certain PO₄ level anymore.
I calculated the "deadly" 117:1 N:P ratio for various phosphate levels. Nitrate levels above those stated in the table would bleach the corals if the N:P ratio still mattered at phosphate levels above 0.03ppm.

PO₄ (ppm)	NO₃ (ppm)
0.03	2.29
0.04	3.06
0.05	3.82
0.06	4.58
0.07	5.35
0.08	6.11
0.09	6.87
0.10	7.64

I don't think having 0.10ppm PO₄ and 10ppm NO₃ is causing corals to bleach and neither does 0.03ppm PO₄ and 5ppm NO₃ (at least not in my tank #AnecdotalEvidence).

There has to be something to the statement that at some point the ratios don't mean so much anymore in my opinion. Otherwise, many tanks would crash right now.

Edit: Obviously you can go so low with phosphate and/or nitrogen that stuff dies. But that's not what the paper is about, and I don't think anyone is doubting that.

The discussion has not factored in the fact that the large variability in hobby measurement of phosphate and nitrate results in aquarium ratios being all over place. You really don’t know what your ratio is. Let’s drop ratios from the discussion, and focus on the measured amounts of each species.

 

[Dan_P]

now the chaos is perfect:

We have Opinion A saying nutrient ratios matter, even in tanks with higher nutrient levels.

Then we have Opinion B saying nutrient ratios matter more when absolute values are low like in nature but less when they are a bit higher like in most reef tanks.

And now there is Opinion C saying they don't matter and absolute values are the most appropriate measure

I love it

Once you remove opinions and assertions about ratios, which we cannot actually determine with any accuracy, the world becomes simpler.

 

[EnterName]

The discussion has not factored in the fact that the large variability in hobby measurement of phosphate and nitrate results in aquarium ratios being all over place. You really don’t know what your ratio is. Let’s drop ratios from the discussion, and focus on the measured amounts of each species.

It hasn't even factored in that NO₃ isn't the only N source and PO₄ the only P source. So obviously precise N:P ratios are far to complex for hobbyists to measure.

I'm just saying if you can detect at least 0.03ppm PO₄ you are above the study's threshold regardless of other P and N sources and that might explain why we are fortunate enough we can focus on absolute levels and don't need to worry too much about ratios anymore, even if there certainly still is some effect.

 

[Lasse]

Excuse a youngster but in this statement it seems to me that you contradict yourself

hat the large variability in hobby measurement of phosphate and nitrate results in aquarium ratios being all over place. You really don’t know what your ratio is. Let’s drop ratios from the discussion, and focus on the measured amounts of each species.

If you can´t use your measurement in order to get a ratio because large variability in hobby measurement - how can we focus on the SAME measurement of each species? What you say is that we can never relay or transfer a measurement from one testperson/aquarium to another testperson/aquarium


Sincerely Lasse