Reef Tank Flow Rate Calculator
Calculate the ideal Gallons Per Hour (GPH) for your aquarium
Recommended Flow Rate
0 Liters Per Hour (LPH)
Understanding Reef Tank Flow Rates
In a reef aquarium, water movement (flow) is just as critical as lighting and water chemistry. Flow performs several vital functions: it delivers food to sessile organisms like corals, removes metabolic waste products, and facilitates gas exchange at the water's surface.
How much flow do I need?
Flow is typically measured in Turnover Rate, which is the number of times the total volume of your tank moves through your powerheads and pumps in one hour. The requirement varies significantly based on what you are keeping:
- Soft Corals (Leathers, Mushrooms, Zoanthids): These prefer moderate, gentle flow. A turnover of 10x to 20x the tank volume is usually sufficient.
- LPS (Large Polyp Stony – Hammers, Torches, Acans): These need enough flow to keep their fleshy polyps moving without tearing the tissue against their sharp skeletons. 20x to 40x is ideal.
- SPS (Small Polyp Stony – Acropora, Montipora): These inhabit high-energy reef crests. They require high, turbulent flow to prevent detritus from settling. 40x to 100x+ is common for dedicated SPS tanks.
Calculating Total Flow vs. Return Flow
It is important to distinguish between "Total Flow" and "Return Flow." Return flow refers specifically to the water moving from your sump back to the display (usually 3x to 5x turnover). The remaining flow required should be provided by internal powerheads or wavemakers to create the necessary turbulence within the display tank.
Example Calculation
If you have a 50-gallon tank intended for LPS corals (30x turnover):
50 Gallons × 30 (Turnover) = 1,500 GPH Total Flow