Calculate daily total ammonia nitrogen (TAN) production from daily feed amount and protein content. Essential for RAS biofilter sizing and aquaculture system design.
Every fish converts protein in its food into ammonia (mostly NH3 and NH4+) which is excreted across the gills and through waste. Knowing how many grams of total ammonia-nitrogen (TAN) your stock produces per day is fundamental to sizing biofilters, planning aquaponic systems, and predicting how quickly a new tank will cycle. This calculator translates daily feed mass and protein percentage into grams of TAN per day and grams per hour, the two numbers biofilter manufacturers and aquaponic designers actually use.
The standard TAN-from-feed equation multiplies daily feed mass by protein fraction by an excretion coefficient (typically 0.092, representing the share of feed nitrogen that exits as TAN). We assume a feed crude-protein content you provide, default the nitrogen-to-protein ratio to 6.25, and report results in both grams per day and grams per hour to support continuous-flow filter sizing. Aquaponic system designers use the per-hour figure to match nitrification rates with hydraulic residence time.
Enter daily feed amount (kg) and the crude protein percent on the feed label. The calculator estimates Total Ammonia Nitrogen (TAN) excreted by the fish per day and per hour.
Formula: TAN = feed × protein × 0.16 × 0.80. It assumes 16% nitrogen in crude protein and 80% of nitrogen excreted as ammonia — standard RAS engineering numbers from Timmons & Ebeling.
Use the g/hr output to size biofilters and the hourly peak ammonia load on your nitrification media. Real excretion fluctuates with feeding schedule — size to the hourly peak, not the daily average.
TAN (Total Ammonia Nitrogen) is the sum of NH3 + NH4⁺ excreted by fish. It is the primary nitrogen waste product and the main load on the biofilter. Knowing daily TAN lets you size nitrification capacity correctly and prevent ammonia spikes.
It is the standard estimate from Timmons & Ebeling (Recirculating Aquaculture, 2010). 16% of crude protein is nitrogen and roughly 80% of that nitrogen is excreted as ammonia. Real values range from 0.70 to 0.90 depending on species, life stage, and feed digestibility.
Yes. High-protein feeds (45–50%) produce more TAN per kg than low-protein feeds (28–35%). Low-pollution formulations with higher digestible protein output less ammonia per gram. Always use the actual crude protein percentage from the feed label.
Fish excrete most ammonia 1–6 hours after feeding. If you feed once a day, the hourly TAN load can be 2–3× the daily average for several hours. Sizing biofilters and oxygen supply to the hourly peak prevents post-feeding ammonia spikes.
Warmer water increases fish metabolism and feeding, which raises TAN output. A tilapia system at 28°C produces noticeably more TAN per kg of feed than a salmonid system at 14°C, even with the same feed. Adjust expectations seasonally in non-temperature-controlled systems.