How to use this calculator
- Enter or choose fish tank volume.
- Enter or choose volume in.
- Enter or choose tank turnovers per hour.
- Enter or choose total grow-bed volume.
- The pump flow needed updates as you type. Use Copy result or Share to keep it.
Method
Flow = Tank volume × Turnovers per hour; Cycle time = 60 ÷ Turnovers; Ratio = Grow bed ÷ Tank
- Turnovers per hour
- how many tank volumes the pump moves each hour
- Grow bed
- volume of media or channels the water flows through
Worked example
- Flow = 1,000 L × 1 per hour = 1,000 L/h = 16.67 L/min.
- In US gallons: 1,000 ÷ 3.785 = 264.2 gph.
- Grow bed ratio = 500 ÷ 1,000 = 0.5.
A 1,000 L fish tank turned over once an hour needs a pump delivering 1,000 L/h (about 264 US gph) at the working head.
What the result means
Pump ratings fall as the lift (head) rises, so pick a pump whose curve delivers this flow at your total head, including pipe losses. Use the pump power calculator to estimate the electricity.
Assumptions and limits
- The whole flow passes through the fish tank.
- Pipe friction, head and pump curves are not modelled.
Questions
How many turnovers per hour do I need?
It depends on stocking density and filtration. Heavier stocking needs more flow for oxygen and waste removal; follow your system design or supplier.
Why does my pump deliver less than its rating?
The rating is usually at zero head. Every metre of lift and every fitting reduces the flow; check the pump curve.