Amino Acid dosing causes carbon dosing like results

Tripod1404

Active member
Hello Guys,

About 2 months ago, my nitrate and phosphate levels dropped to very low values (0.5 - 0.2ppm NO3 and 0 to 0.004 PO4). So I decided to gradually educe and carbon dosing. While doing so I was adding amino acids every other day.

Than I realized something very strange. I was adding aminos to increase nitrate. But the outcome was the opposite, it was causing nitrates to drop. This in mind I didnt dosed amino acids for 3 days. Nitrate raised to about 2-3ppm. That day I does aminos and the next day it was back to ~0.5ppm range. I was able to repeat this one more time.

While thinking about it from a biochemical perspective, it realized it might not be that surprising. 18 of 20 naturally occurring amino acids are glucogenic. Meaning they can be converted to glucose. Two remaining amino acids are ketogenic and they can be converted to ketone bodies, which are the precursor of fatty acids (5 of the 18 are both glucogenic and ketogenic).

So in my opinion, adding amino acids cause a carbon dosing like effect because bacteria convert amino acids to glucose. But the interesting part would be what happens to the nitrogen? I am not surprised that you can maintain a bacterial population, but I am surprised that nitrate can go lower. Adding amino acids introduce carbon as well as nitrogen. So I would expect the outcome to be "no change" at best and an increase in nitrate as a more reasonable assumption.

To be honesty I dont know what exactly is going on. Maybe bacteria are using the carbon and excreting the nitrogen in some nitrogenous waste form like ammonia, nitrate or nitrate. Afterwards other bacteria, algae, clams or corals might be picking it up.

Another possibility is the complete breakdown of large amino acids into multiple sugars (here I use sugars as a term for carbon sources). Carbon/Nitrogen ratio of simplest amino acid glycine is 2 carbon atoms and 1 nitrogen atom. But larger amino acid has much bigger C/N ratios, for instance tryptophan has 11 carbons and 2 nitrogen, phenylalanine has 9 carbons and 1 nitrogen. Metabolically, bacteria are very efficient, so they might be able to breakdown large amino acids and convert them to multiple sugars or other molecules. This mean they might even need more nitrogen and hence the drop in nitrate.From a very simplistic point of view, from 2 phenylalanine molecules you have enough carbon to built 9 glycine molecules. But two phenylalanines only supply you with 2 nitogens but you would need 9 nitogens for 9 glycines. So there is a net need for 7 nitrogens or 7 molecules of nitrate. This might be the reason for the reduction in nitrate. More so if the commercial amino acid supplements have a high proportion of large vs. small amino acids.

I was wondering if any of you had similar experiences.
 
Your theory is basically correct. I know this has been covered in threads on here a few times but they may be very hard to find. Several years ago when carbon dosing was first catching on, people noticed that dosing some commercial amino acid supplements had similar effects, and it was pointed out that amino acid dosing is basically a method of carbon dosing.
 
Your theory is basically correct. I know this has been covered in threads on here a few times but they may be very hard to find. Several years ago when carbon dosing was first catching on, people noticed that dosing some commercial amino acid supplements had similar effects, and it was pointed out that amino acid dosing is basically a method of carbon dosing.

I wonder if there is any benefit of dosing amino acids (ideally large ones) in the place of ethanol/methanol or acetic acid. A benefit that would justify the cost.
 
Other carbon sources are so vastly cheaper. And I don't know of any evidence that the amino acids have a positive effect beyond the carbon source but then again I haven't looked.

I have never used aminos myself but I know of a few local tanks where aminos were dosed and eventually the tank was switched to another form of carbon and similar results were achieved.
 
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