Aquarium Filter Turnover Calculator
Measure actual flow, GPH/LPH, turnover rate, and circulation. Visualize water movement and compare against species-specific targets.
🐠 Tank & filter specs
💡 Manufacturer ratings are often measured with no media or head loss.
Leave blank to estimate from manufacturer rating.
📊 Turnover results
Turnover rate
5.0x
tank volumes / hour
Processed per hour
200 GPH
actual flow
Circulation
5.0x
volume exchanges / hour
vs target
✔ Meets target
Target: 5x
⚠️ Manufacturer flow rates are often measured under ideal conditions (no media, no head loss, no restrictions). Actual flow in a running aquarium is typically 30–50% lower. Use the actual flow field when possible.
💧 Live flow simulation
Flow speed reflects turnover rate. More arrows = stronger circulation.
Understanding aquarium turnover rate
Turnover rate measures how many times your filter processes the entire aquarium volume in one hour. It's the most practical way to compare filtration power across different tank sizes. A 40-gallon tank with a 200 GPH filter has a turnover of 5x — meaning the entire water volume passes through the filter five times per hour.
But advertised flow rates can be misleading. Manufacturers often measure flow with no filter media, no head height, and no restrictions. In a real aquarium, media clogs, tubing bends, and gravity all reduce actual flow. That's why our calculator lets you enter actual flow if you've measured it — or it will estimate based on typical restriction.
🔹 Advertised vs actual flow
Manufacturer GPH is usually measured at zero head. Real-world flow drops 30–50% with media, tubing, and height. Always aim for a turnover based on actual flow, not the box rating.
🔹 Filtration media matters
Sponges, ceramic rings, and filter floss increase biological capacity but also increase resistance. A heavily packed filter may reduce flow by half compared to an empty canister.
🔹 Species & tank considerations
Bettas prefer gentle flow (3–5x), while SPS reef tanks need 15–20x. Goldfish produce lots of waste — aim for 8–10x. Always observe fish behavior: gasping or hiding from flow means it's too strong.
🔹 Circulation vs turnover
Turnover measures filter throughput. Circulation is broader — it includes powerheads and wavemakers that move water without passing through filter media. Both matter for a healthy tank.