Aquarium Filter Size & Flow Calculator

Verified manufacturer filter presets

For a faster lookup, the calculator includes current first-party presets for Fluval AC, Fluval 07 and Seachem Tidal filters. The table keeps each manufacturer’s own flow label intact instead of treating every GPH value as the same measurement. Presets were rechecked September 30, 2026.

This preset list is a convenience layer, not a cross-brand performance ranking. You can still enter any exact manufacturer model manually when it is not listed.

Why manufacturer range comes first

The exact model's documented aquarium range is a stronger first boundary than applying one generic GPH multiplier across unrelated filters. Some manufacturers publish a minimum and maximum; others publish only an “up to” ceiling. The calculator preserves that distinction instead of inventing a missing lower limit.

If you do not know the aquarium's practical water volume, use the aquarium volume calculator first. Then use the aquarium filter size guide for the broader decision around livestock flow tolerance, media capacity, maintenance and tank layout.

Flow labels are not interchangeable

Manufacturer-specific labels are not interchangeable. Pump output, maximum flow rate and filter circulation can describe different measurements. A numerical ratio is only useful if the label stays attached to the number that produced it.

The calculator therefore reports “published label ÷ tank volume” rather than silently calling every result turnover or actual circulation. It does not convert a manufacturer label into installed flow because media loading, hose routing, head height, fouling and flow adjustment can change operating conditions.

How to use the result

A tank inside the manufacturer's range is a candidate, not an automatic recommendation. Compare media architecture, intake safety, return current, physical fit and maintenance burden before choosing. Our best aquarium filters guide covers mixed architectures, while the HOB filter guide and canister filter guide narrow the decision by filter type.

If the livestock itself is the limiting factor, move from the calculator to a species-specific decision page. For example, our goldfish filter guide provides a goldfish-specific shortlist based on documented tank fit, media access and current control rather than a universal turnover rule.

If tank size is the constraint, use a size-specific guide after checking the manufacturer range. Our 40-gallon filter shortlist compares overlapping HOB and canister options without treating unlike flow labels as interchangeable.

A tank above the documented maximum is a clear reason to reject that exact model. A tank below an explicitly documented minimum also sits outside that published range. When only a maximum is published, this tool deliberately does not infer a lower boundary.

What this calculator does not decide

It does not establish biological capacity, cycling status, oxygenation, safe stocking, noise, durability or real installed flow. It also does not say that a larger filter is automatically better. A larger model can add media capacity or circulation headroom, but it can also create excessive localized current or make servicing harder.

Use current manufacturer documentation for the exact model and keep unlike hydraulic labels separate when comparing brands or filter families.