Number chasing No3 & Po4

[Rob Top1]

Not so long ago we seemed content to say we had no Po4 or No3 if it was under .25 and 5 respectively as that was as low as most affordable kits went. As tests have gotten better and more affordable we are able to test our Po4 down to .01 and No3 .25 before we can call it zero. As such it seems like some are chasing that number. I have read that Po4 above .03 is a problem. So we pile on the GFO and GFA carbon dose and test trying to get these nutrients ever lower. Now I am fully aware of how elevated nutrients will negatively effect calcification. But what real difference will I see by lowering these further. Currently my Po4 is at .15 and No3 at .75. If I am able to achieve zero will my acros explode in growth? I am pleased with thier current growth but like all of us wonder how much better could it be. Can it get better and if so what do I do to get there? Carbon dosing?

 

[Randy Holmes-Farley]

The real difference you will see will depend on how far you lower it, and whether you have any algae problems at the moment. I do not believe that you will typically see better coral growth alone by dropping phosphate from 0.02 to 0.01 or lower values. That said, almost no one can accurately measure 0.01 ppm phosphate and distinguish it from 0.00 and 0.02 ppm. There is no home method of accurately doing so.

Lower phosphate far enough and corals will become pale and not grow well. But many people claim an intermediate phosphate value that they think is optimal for color. Maybe in the 0.01 range.

Then there is the starvation effect, where you lower nutrients to the point where the zoox are "starving" and do not exist in as high of numbers in the coral. Since they are golden brown, colors can appear to be more intense (ala zeovit) with fewer of them present. To make up for the starving zoox, such systems often require feeding the corals organic compounds, such as amino acids.

 

[Rob Top1]

As far as algea goes I do have to clean the glass every couple few days for a clear view. Also if I don't coraline will start spotting it up with in a week. Due to the coraline and needing to keep it clean to prevent its build up I really don't mind the diatoms. Is it possible to eliminate the diatoms by lowering the Po4 and No3?