Safe carbon dosing?

[Belgian Anthias]

The C/N ratio = protein content of the feed

The C:N ratio of a feed is generally calculated as follows: regardless of the protein content, the carbon content of a feed is always considered to be 50%. To get the C:N ratio, one has to find the N%. This is done by dividing the protein by 6.25. For a shrimp feed with a crude protein of 21%, the N content is 21 divided by 6.25 = 3.36%. Thus, the C:N ratio of the food is 50 divided by 3.36 = 14.88:1 or nearly 15:1 .(PohYongThong2014) ref: MB biofloc CMF De Haes 2021

Correct dosing of organic carbon reduces nitrate production but ensures that sufficient nitrate remains available to sufficiently support and keep going all essential processes where nitrate is required.
Nitrate formation ensures that about 16% of produced NO3-N can be exported naturally.

This is NOT possible if dosing is based on the nitrate level.

 

[GARRIGA]

I've dosed NoPox along with MB7 in my test tank. Brought post cycle nitrates down from 160 ppm plus to less than 5 ppm. Water was cloudy for a few days each dose but cleared up naturally. No sump. No skimmer. No socks. Just lots of pumice under a slow flow to extend contact time and carbon along with filter floss to remove yellows and fine particulates. Feed heavily. Just fish at the moment plus it's an experimental tank testing denitrification and alkalinity bugger through denitrification and use of Reborn as initial nitrification media.

From my observations. NoPox seems easy enough to use and in the beginning to lower the high nitrates I purposefully overdoses since it was still fish-less and wanted to see the affects. Had to add phosphates to finally see results. Have had to do that every time since my tank tends to be phosphate deficient at times. Don't know why. However, last phosphate dose got a nasty outbreak of GHA which has now subsided to nothing more than a few isolated tiny patches and looks more like turf then GHA.

I'm no longer carbon dosing because I'm trapping detritus and allowing filtration to break it down therefore adding carbons naturally. Goes to show that with proper filtration less is needed and I haven't performed a water change since last getting nitrates down to 5 ppm and wanting to reduce salinity to brackish so I could introduce freshwater Mollies then test acclimating them to full salt. Test tanks are fun. Better to fail here then with the DT.

As to the Redfield ratio. True believer yet not convinced it's an exact ratio vs just having both elements to reduce the other. That's been my observation although limited in time applied I have seen enough results to believe we don't need to be exact and just ensure both are present then the tank should balance which is my ultimate goal. KISS.