How much ammonia does your feeding produce?

[Azedenkae]

Heyo! I want some data from you guys if possible.

I want to see how much ammonia your feeding is producing. Could you describe:
1. How often you feed.
2. How much ammonia is produced from your feeding.

To calculate the latter, for each type of food multiply amount fed (in mg) x % protein (should be stated on label) x 16% (nitrogen in protein) / tank volume (in litres).

For example, I feed 0.2 grams of NLS pellets a day, i.e. 200 mg pellets. The protein content listed on the container is 39%. My aquarium is 20 gallons, i.e. around 75.7 litres, though actual water volume is only 57 litres. I'd prefer you'd calculate based on true water volume, but tank volume works too.

So for me, it'd be 0.2 x 0.39 x 0.16 / 57 = 0.22 mg/L (ppm) ammonia a day.

Credit for the formula goes to @taricha. I don't know enough about this to come up with it myself. If you feed multiple foods, well here's Taricha's calc:

I would like to know what people's actual food inputs are. It's not hard to know - foods say right on the label what % is protein.
If I feed a cube of mysis, a cube of brine, and a pinch of flake...
mysis: 3.3g x 7.6% protein x 16% N in protein = 40mg N
brine: 3.3g x 3.7% protein x 16% N in protein = 20mg N
pinch of flake: 0.5g x 53% protein x 16% N in protein = 42mg N
Total = input of 40+20+42 = 102mg N in 260L system = 0.39 mg/L of N
if 100% of that protein N went into NH4 that'd give 0.39 x (18 mass NH4 / 14 mass N) = 0.50 ppm NH4

Note #1: No I don't have problems with feeding or looking to change my feeding schedule, this is more so out of curiosity than anything.
Note #2: Yes it is all just an estimations. Still very valuable data though.

 

[taricha]

Here's a bit more info and context. Aquarium systems are complex so it might be tempting to assume all sorts of unpredictable things can happen to food that goes in.
Not really true. Food gets mostly eaten. If not by fish, then by shrimp, crabs, etc. And when it gets eaten, it largely gets turned into ammonia.

"The constant in the ammonia generation equation assumes that protein is 16% nitrogen, 80% nitrogen is assimilated by the organism, 80% assimilated nitrogen is excreted, and 90% of nitrogen excreted as TAN [Total Ammonia- Nitrogen] + 10% as urea.
....
In addition for the example used in this paper, research data suggests that 90% of the nitrogen assimilated by marine shrimp is excreted as TAN and urea."
-Aquaculture paper on ammonia processing

So the takeaway is, the large majority of food nitrogen that goes into your tank really does become ammonia, regardless of the system details, and who exactly eats it.

(Now, what happens to the ammonia after that is much more variable and complicated.)