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Aquaponic System Water Needs Estimator

The Aquaponic System Water Needs Estimator calculates replacement water for an aquaponic system from total system water volume, expected daily loss rate, planning period, and additional planned water exchanges. It is useful for sizing make-up water supply, estimating routine top-up demand, or comparing how a change in evaporation, splash, purge, or maintenance practices affects total replacement volume.

Daily loss is entered as a percentage of the system volume, which makes the model easy to scale across differently sized systems. Planned exchanges are added separately as a percentage of system volume per event so occasional maintenance or deliberate water replacement is not hidden inside the routine loss rate. The estimator assumes the reference system volume remains approximately constant because losses are replenished. Actual losses depend on climate, greenhouse conditions, plant transpiration, leaks, filter cleaning, fish operations, and management practices, so site measurements are the best basis for the percentage assumptions.

Aquaponic water balance

L
%/day
days
%
events
Result
—
replacement water required
Routine top-up water—
Planned exchange water—
Average replacement per day—
Replacement vs system volume—

1. Enter system volume
Use the normal operating water volume of the fish tanks, sump, grow beds, and other water-holding components included in your system boundary.

2. Set routine daily loss
Enter the estimated percentage of system volume replaced each day because of evaporation, transpiration, leaks, splash, purge, or similar losses.

3. Choose the planning period
Enter the number of days for supply or top-up planning.

4. Add planned exchange size
Enter the percentage of system volume replaced during one deliberate exchange or maintenance event.

5. Enter exchange events
Use zero if no planned exchanges occur during the period; otherwise enter the number of events.

6. Review replacement demand
The result separates routine top-up from planned exchange water and shows the average daily requirement.

Routine top-up = System volume × (Daily loss % ÷ 100) × Days Planned exchange water = System volume × (Exchange % ÷ 100) × Number of events Total replacement water = Routine top-up + Planned exchange water

What the result means

The result is the fresh water volume needed to replace the modeled routine losses and planned water exchanges during the selected period.

The model treats system volume as effectively constant because lost water is replenished. It does not model rainfall capture, water quality limits, or biological water production/consumption in detail.

Given: 15,000 L system volume, 1.2% daily loss, 45 days, 4% exchange size, and 3 exchange events.

Calculation: Routine top-up = 15,000 × 0.012 × 45 = 8,100 L. Planned exchanges = 15,000 × 0.04 × 3 = 1,800 L. Total = 8,100 + 1,800 = 9,900 L.

Result: Estimated replacement water: 9,900 L.

That averages 220 L/day over the planning period, including the planned exchanges.

What should be included in daily water loss?

Include recurring non-recovered losses that are reasonably represented as a percentage of system volume, such as evaporation, transpiration, filter purge, splash, and small leaks. Keep scheduled exchange events separate if you enter them in the exchange fields.

Does the calculator compound the daily percentage loss?

No. It assumes the operating volume is restored with top-up water, so the same nominal system volume is used each day.

Should rainfall or captured condensate reduce the result?

They can reduce purchased or external make-up water, but this calculator does not include them directly. Subtract dependable recovered supply from the calculated replacement need separately.

Can water exchange be zero in aquaponics?

Yes. Enter 0% or zero events when your scenario assumes no planned exchanges. Routine losses may still require make-up water.

How does this compare with a hydroponic water-needs estimate?

Both address replacement water, but this aquaponic version starts from total system volume and percentage losses, while the hydroponic version starts from plant demand and recovery assumptions.