Aquarium Canister Filter Size Calculator

How this calculator works

The calculator estimates desired actual turnover, then adjusts upward for media, hose height, and stocking.

When to round up

Round up for messy fish, long hoses, packed media baskets, and planted tanks with high circulation needs.

Formula and assumptions

This calculator uses the inputs above to turn a practical planning question into a usable estimate. The result should be treated as a starting point, because product ratings, room conditions, material waste, and real-world use can vary.

Formula: ceil(gallons * turnover * mediaLossFactor * stockingFactor / 25) * 25

Example calculation

Example inputs: Tank volume: 55 gallons; Target turnover: 5 x/hour; Media/height loss factor: 1.35; Stocking factor: 1.1. With those values, the calculator returns 425 GPH rated flow. Look for canister filter rated flow around 425 GPH rated flow.

Example scenarios

• Simple case: Use the default inputs as a quick baseline. In this sample, the result is 425 GPH rated flow, which gives you a practical number to compare against product labels or project instructions.
• Round-up case: If the room, project, appliance, or aquarium setup has extra uncertainty, use the same result as a minimum and choose the next practical size, package, or capacity.
• Cross-check case: If cost, material quantity, or equipment size affects another decision, open one of the related calculators below and make sure the numbers agree with each other.

Quick reference chart

Common planning mistakes

Avoid using rough guesses for every input, forgetting waste or safety margin, and treating the estimate as a guaranteed final number. Measure the space, round up when buying materials or equipment, and compare the result with product labels or project instructions.