Calculate required biofilter surface area (m²) and bio-media volume (L) to remove your daily TAN load. Supports MBBR, trickling filter, and fluidized bed configurations.
A biofilter is only useful if its surface area and oxygen supply can keep up with the daily ammonia load coming from livestock. This calculator takes your daily TAN production in grams, the type of biofilter media you intend to use (MBBR K1, trickling tower, fluidized bed, or a custom value), and returns the required active media surface area in square meters, the corresponding media volume in liters, and a recommended turnover. The result is a defensible, engineering-grade biofilter spec rather than a marketing rule of thumb.
Each media type has a characteristic ammonia removal rate (grams TAN per square meter per day) and a specific surface area (square meters per cubic meter of media). MBBR K1 typically removes 0.3-0.5 g/m2/day and offers about 500 m2/m3 of protected surface; trickling filters can hit 0.7-1.0 g/m2/day with very high oxygen; fluidized sand is the densest. The calculator divides your daily TAN by the chosen removal rate to obtain required area, then divides by specific area to obtain media volume.
Enter your daily TAN load (from the Ammonia Production calculator), then pick a bio-media type. The preset auto-fills the nitrification rate (g TAN/m²/day) and specific surface area (m²/m³) for that media.
Required surface area = TAN load ÷ nitrification rate. Media volume = required area ÷ specific surface × 1000. MBBR K1 gives a balanced trade-off; fluidized beds are more compact but require tighter flow control.
Add a 20–30% safety factor in real builds. Nitrification rates drop at low temperatures (<15°C) and low dissolved oxygen (<4 mg/L). Cold-water salmonid systems often size to half the listed rate.
MBBR K1 plastic media is the most common choice for warm-water RAS — it gives 500–800 m²/m³ specific surface area and tolerates fluctuating loads. Fluidized bead filters are more compact (1500+ m²/m³) but require precise flow control. Trickling filters are simplest but largest.
K1 is a small plastic ring (1 cm diameter) used in Moving Bed Bioreactor (MBBR) systems. The media floats freely in an aerated tank and biofilm grows on the protected inner surface. K1 is the industry standard for medium- to large-scale aquaculture biofilters.
Calculated nitrification rates assume optimal pH (7.0–8.0), DO >5 mg/L, and stable temperature. Real systems experience excursions — feeding peaks, water-change disturbances, or seasonal cooling — that temporarily lower nitrification capacity. A safety margin keeps the biofilter ahead during these events.
Yes — significantly. Nitrification rates are roughly halved at 15°C compared to 25°C. Cold-water salmonid systems should size biofilters for the lowest expected operating temperature, typically using 50–60% of warm-water rates.
Ammonia and nitrite both stay below 0.25 ppm with a stable feeding load. A new biofilter takes 4–8 weeks at warm temperatures and longer in cold water. Stock the system gradually — start at 25% of design feed and increase weekly while monitoring water quality.