Recirculating Aquaculture Energy-Feed Balance Calculator
This RAS calculator converts a daily feed plan, feed conversion ratio, and survival assumption into feed-derived harvestable biomass, then compares that harvest with electricity, makeup water, labour, feed, and mortality-disposal costs. Its per-kilogram measures show how biological performance and continuous equipment loads can affect operating margin during one grow-out cycle.
Start with the supplied RAS values, then substitute your own ration, utility tariff, water-exchange rate, and prices. The calculator is intended for internally consistent operating comparisons; it is not a tank-design, water-quality, or complete farm-valuation model.
RAS energy-feed balance formulas
This RAS energy-feed balance derives harvest from feed offered during the cycle rather than from nominal standing-biomass capacity. Feed offered is converted to growth using FCR and then reduced by the survival rate:
Total feed in the RAS cycle is daily feed multiplied by grow-out days. Feed per kilogram of harvest therefore reflects both FCR and survival losses, so it is not identical to the entered FCR when survival is below 100 percent.
RAS electricity combines the continuous pump and aeration loads with the daily heating or cooling energy entered for the cycle:
Makeup water in this RAS calculation is based on the system volume and entered daily exchange percentage. It is converted to litres only when the calculator reports water use per kilogram of harvest.
The calculator applies the entered unit prices to the quantities above. Feed and electricity costs use total feed and total energy respectively, while labour is charged once for every cycle day.
RAS revenue is harvestable biomass times harvest price. Operating cost includes feed, electricity, labour, makeup water, and mortality disposal; margin is revenue less those included costs.
The calculator divides energy, feed, water use, operating cost, and margin by harvestable biomass to produce per-kilogram measures. These measures are operating comparisons rather than a full cost-of-production statement.
Interpreting RAS energy, feed and margin outputs
The RAS output panel reports planning indicators for the feed and utility assumptions you enter. Read the indicators together, because an attractive cost per kilogram can still depend on a survival rate, feed efficiency, or energy load that may be difficult to maintain.
- Energy per kg harvest — total continuous and heating/cooling energy divided by feed-derived harvestable biomass. It includes the pumps, filtration, aeration, and oxygenation load entered in the form.
- Feed per kg harvest — total feed offered divided by harvestable biomass. Survival losses make this figure higher than the entered FCR.
- Operating cost per kg — feed, electricity, water, labour, and mortality disposal costs divided by harvestable biomass. It is an operating comparison, not a complete cost of production.
- Net margin per kg — harvest revenue less those operating costs, expressed per kilogram of harvest. A positive result covers only the costs included by this tool.
- Water use per kg — makeup water from daily exchange, converted to litres and divided by harvestable biomass.
For a feed-driven RAS plan, first check whether daily feed, cycle length, and FCR imply a harvest quantity compatible with system volume and the intended stocking-density target. The volume and stocking-density fields do not cap calculated harvest; system volume is used here to calculate makeup water from the entered exchange percentage.
Worked example: feed-driven warmwater RAS cycle
The displayed RAS inputs describe a 180-day cycle with 120 kg of feed each day, an FCR of 1.25, and 92 percent survival. The calculator treats total feed as 21,600 kg and converts it to 17,280 kg of growth before survival, giving about 15,898 kg of harvestable biomass.
With 18 kW for pumps and filtration, 12 kW for aeration and oxygenation, and 80 kWh each day for heating or cooling, energy totals 144,000 kWh for the cycle. At $0.11 per kWh, that is $15,840 in electricity cost. Feed at $1.85 per kg costs $39,960 before the other operating items are added.
The same RAS inputs produce 405 m³ of makeup water at a 1.5 percent daily exchange rate. Labour is charged for every cycle day, and disposal is charged on the difference between pre-survival growth and harvestable biomass. These details matter because a low FCR alone does not guarantee a low delivered cost per kilogram.
Use the live results rather than this illustration when revising a ration, energy tariff, or harvest price. A practical RAS comparison changes one assumption at a time, then checks whether the resulting feed-derived harvest still makes sense for available tank capacity and oxygen-management limits.
Comparing RAS operating scenarios and benchmarks
The calculator generates three RAS cases after you submit the form. Baseline uses your values; Energy squeeze applies a 30 percent increase in electricity price and 20 percent more heating or cooling energy; Feed optimization uses a 10 percent lower FCR and a 12 percent higher feed price.
| Scenario | What changes | What to examine |
|---|---|---|
| Baseline | Your feed, energy, water, and price inputs | Whether margin and per-kg intensity meet your planning target |
| Energy squeeze | Higher electricity price and higher heating/cooling demand | Exposure of energy per kg and margin to utility conditions |
| Feed optimization | Lower FCR with a higher unit feed cost | Whether less feed offsets the premium diet cost |
For RAS scenario work, vary feed offered, FCR, survival, and equipment loads deliberately rather than treating any one result as a forecast. The download button exports the three generated cases as a CSV file for review alongside supplier quotes, utility bills, or a separate engineering model.
RAS energy-feed balance assumptions and limitations
This RAS energy-feed balance simplifies feeding, biology, and operating loads into cycle averages. Keep these boundaries in mind when applying the results:
- Harvest is calculated from daily feed, cycle length, FCR, and survival; the entered tank volume and stocking density do not constrain harvest biomass.
- Daily feed, continuous power, heating/cooling energy, labour, and water exchange are held constant over the whole cycle, although real grow-out profiles change as fish grow and seasons shift.
- Survival is applied as one cycle-wide percentage. The model does not assign timing, disease effects, treatment costs, or production disruption to mortality events.
- Makeup water equals system volume times the entered daily exchange fraction times cycle days; it does not model sludge volume, evaporation, leaks, or treatment performance.
- Included costs are feed, energy, water, labour, and mortality disposal. Capital equipment, depreciation, financing, insurance, fingerlings, treatments, permits, taxes, and maintenance replacement are outside the calculation.
- Currency values are nominal inputs. The calculator does not adjust for inflation, interest, taxes, or exchange rates.
Treat this RAS balance as a transparent screening calculation. Before committing to a stocking plan, reconcile its feed-derived harvest with tank capacity, oxygen supply, filtration performance, biomass growth curves, and operating records for the specific farm.
Plan RAS feed and energy costs before committing to a grow-out cycle
Recirculating aquaculture systems rely on continuous mechanical support: recirculation pumps, filters, aeration or oxygen systems, and temperature control may operate for every day of a cycle. This calculator places those recurring loads beside daily feed, survival, and selling price so a RAS operator can see the operating-margin consequence of a proposed feeding plan.
The form begins with tank volume and stocking density because they provide useful context for checking the scale of a RAS plan. In this implementation, however, daily feed offered drives harvest. Entering daily feed and cycle length establishes total feed; dividing by FCR estimates growth, and applying survival estimates harvestable biomass. Compare that result separately with the biomass that the tanks and operating system can safely support.
Feed conversion ratio expresses kilograms of feed per kilogram of growth before survival. A lower FCR reduces the amount of feed needed for a given amount of calculated growth, but the model also lets a premium feed cost more per kilogram. This is why the feed-optimization scenario changes both FCR and feed price instead of assuming every efficiency improvement is free.
Mechanical energy is calculated from pump and aeration power multiplied by 24 hours and cycle days. Heating or cooling is already a daily kWh value, so it is multiplied only by cycle days. Electricity cost is applied to the resulting total kWh. Water cost uses system volume, the daily exchange percentage, cycle length, and the makeup-water price.
Labour is a daily cost over the RAS grow-out period. Mortality disposal is charged on estimated growth that does not remain harvestable after the survival adjustment. Revenue uses harvestable biomass and the harvest price. The model then subtracts its included operating costs from revenue to report a margin, not an EBITDA measure or a full accounting profit.
The RAS feed and energy relationships are:
Mortalities are . RAS energy consumption combines the continuous loads with daily heating or cooling:
Here and are pump and aeration loads in kilowatts, while is daily heating or cooling energy. Water use is system volume times exchange fraction times cycle length. The outputs include energy per kilogram , feed per kilogram , operating cost per kilogram, margin per kilogram, and water use per kilogram.
The scenario table is generated from the current RAS form values, so it updates whenever you calculate. It does not test engineering limits, validate a ration against standing biomass, or warn about oxygen, ammonia, or solids capacity. Use those checks alongside the financial comparison.
For the displayed inputs, baseline results are approximately 9.06 kWh/kg, 1.36 kg feed/kg, $6.52/kg operating cost, $1.28/kg margin, and 25.47 L/kg of makeup water. Those values follow the calculator's feed-driven harvest calculation and change whenever the underlying inputs change.
When reviewing a RAS proposal, prioritize the assumptions with the largest cycle-wide effect: daily feed, FCR, survival, labour rate, continuous electrical load, and harvest price. Confirm units carefully—power is entered in kW, heating/cooling in kWh per day, water cost in dollars per cubic metre, and water output in litres per kilogram.
How the calculator models a RAS grow-out cycle
This RAS calculator works per cycle. It converts average daily feed to feed-driven biomass, applies the survival percentage, scales energy and water use over the entered days, and then allocates included operating costs across harvestable kilograms.
At a high level, the calculator follows these RAS steps:
- Multiply daily feed by cycle length to obtain total feed offered.
- Divide total feed by FCR and apply survival to estimate harvestable biomass.
- Scale pump, aeration, heating/cooling, and water-exchange inputs over the grow-out cycle.
- Add feed, energy, water, labour, and mortality-disposal costs.
- Express energy, feed, water, operating cost, and margin per kilogram of calculated harvest.
How to use this RAS energy-feed balance tool
RAS farm owners, system designers, consultants, and students can use this calculator to connect daily feed offered, FCR, survival, utility loads, exchange water, and operating prices. It offers a quick feed-driven comparison of harvest, cost, and margin assumptions and can support—not replace—a detailed engineering design or financial model.
Arcade Mini-Game: Recirculating Aquaculture Energy-Feed Balance Calculator Calibration Run
Use this quick arcade run to practice separating useful scenario inputs from common planning mistakes before you rely on the calculator output.
Start the game, then use your pointer or arrow keys to catch useful inputs and avoid bad assumptions.