Phosphorus starvation and nitrogen?

[Randy Holmes-Farley Verified Community Expert]

How does a reefer see what is needed to be dosed or removed? We measure what is present at the moment, what is left over.

Exactly!

If any is left over, there was enough.

If too much is left over, there was possibly too much.

If none is left over, there wasn't enough.

Seems very simple to me.

 

[Belgian Anthias]

Are we saying that a large old sand bed with many organics in it that work their way down to anaerobic zones would push a system to be low in nitrate relative to phosphate?
Contrasted with a bare bottom tank with much less material in anaerobic zones would produce relatively more nitrate vs phosphate?

(Not personally well versed in the differences between the aerobic/anaerobic end products)

I think it will not make a great difference, bare bottom or not. The anaerobic remineralisation rate in anoxic sediments is very low compared to aerobic remineralization, aerobic remineralisation is about 15X faster. But as nitrogen is removed and phosphorus stays, The N/P ratio will decrease due to denitrification, anaerobic remineralization.
In a normal nitrifying biofilm , on bottom sand or on a bare bottom, about 16% of the produced nitrate may be denitrified. Also without a sand bottom , the N/P ratio in the water column will decrease. Also, the C/N ratio is reduced. Nature is keeping it safe.

 

[Belgian Anthias]

Exactly!

If any is left over, there was enough.

If too much is left over, there was possibly too much.

If none is left over, there wasn't enough.

Seems very simple to me.

Logic based on assumptions?
I assume it is about Nitrate and Phosphate management.
Probably this is the logic followed by most starters.

If any is left over, there "was" enough. This is not the same as there "is" enough. The next cell division may double the demand on the place where the action is. If P was leftover maybe this is because there is not enough of something else.
If "too much " is leftover, possibly something is wrong that is limiting growth. Removing what "was "possibly too much may not be a good idea. How determining there really "is" too much?
If none is left over it was not measured at the moment. If Nitrate was not measured does this mean there is not enough nitrogen? A very effective denitrification rate or insufficient nitrification? Insufficient autotrophic carrying capacity? . May we add a supplemental nitrogen source without knowing?

Seems not very simple to me.