Filter Size & Flow Rate Calculator

Size your aquarium filter by net volume, bioload and turnover. See your target effective flow (GPH/LPH) and the rated flow to buy for HOB, canister, or sump—adjusted for media, head height and clogging.

Tank & System

Units Net Water Volume

gal

Internal water volume. If unsure: rated gallons × 0.9. System Type Bioload Level Adult size, feeding, species waste level. Target Turnover (x/hour)

Auto-fill from system & bioload. Number of Filters/Pumps Split rated flow across this many units.

Filter Setup & Losses

Filter Type (planned) Vertical Lift / Head

Rim-to-outlet height (HOB ≈ 0.5–1.0 ft, Canister 2–5 ft, Sump 3–6 ft). Media Packing Heavier media lowers net flow. Clog Allowance

Typical decline between cleanings (0–40%).

Required Flow & Rated Capacity

Enter tank and setup details to see your target effective flow and the rated GPH/LPH to shop for, with a type-by-type comparison.

Recommended Turnover

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Auto suggestion from system & bioload

Target Effective Flow

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What the tank should actually see

Rated Flow Needed (Selected Type)

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Total & per filter (after losses)

Rated Flow Needed — By Filter Type

Filter Type	Loss Model	Total Rated Flow	Per Filter (×N)

Rated flow is what you should shop for on the box/spec sheet to achieve your target effective flow after losses. Scroll or swipe the table if it overflows.

How the Filter Size & Flow Rate Calculator Works

We estimate a recommended turnover (x/hour) from your system type and bioload, then multiply by net tank volume to get the target effective flow. Finally, we compute the rated GPH/LPH required, accounting for filter efficiency, head/lift, media resistance, and clog allowance.

Turnover Suggestions

Planted (gentle): 4–5×
Community: ~5×
Goldfish: ~8×
African Cichlids: ~7×
SA/CA Cichlids: 6–7×
Marine FOWLR: 8–10×
Reef: ~10× display flow (return can be lower; use powerheads)

Quick Tips

Two filters improve circulation and provide redundancy.
Fine pads/floss add resistance—oversize rated flow if you use them.
Head height matters: measure rim-to-return; add 0.5–1 ft for elbows/valves.
Quiet setups: Oversize and run at lower speed when possible.