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CritterCalcs

Aquarium Calculators

Precision tools for freshwater aquarium planning — stocking, heater wattage, filter flow, water changes, CO₂ injection, fertiliser dosing, substrate depth, lighting PAR, tank volume, and brackish salt mixing — based on established fishkeeping science.

Latest in Aquarium

Aquarium Stocking Calculator — Bioload Guide

Freshwater aquarium stocking with bioload, species compatibility, and temperature overlap from a 70+ species database with swim-level balance.

Aquarium Heater Calculator — Wattage Sizing

Size your aquarium heater by tank volume, room temperature, and target tropical temperature. Dual-heater redundancy guidance for tanks over 200 litres.

Aquarium Filter Calculator — Flow Rate Guide

Calculate aquarium filter flow by tank volume and bioload. Turnover targets, media loading factor, and planted-tank adjustment for HOB or canister filters.

Aquarium Water Change Calculator — Schedule

Calculate water change percentage, frequency, and volume by stocking level and planted status. Overdue urgency flag, refill time, and old-tank guidance.

Aquarium CO2 Calculator — Bubble Rate & ppm

Calculate CO2 injection rate, target ppm, diffuser type, and drop checker colour for planted aquariums. Pressurised, DIY yeast, and liquid carbon methods.

Aquarium Fertiliser Calculator — EI Dosing

Weekly macro and micro doses for planted aquariums using EI, PPS-Pro, or lean methods — KNO₃ and KH₂PO₄ in grams, trace mL, cost in USD or GBP.

Aquarium Substrate Calculator — Depth & Bags

Calculate aquarium substrate depth, volume, weight, and commercial bags needed. Covers gravel, sand, aquasoil, and dirted setups with planted adjustments.

Aquarium Lighting Calculator — PAR Guide

Estimate PAR at substrate, photoperiod, and algae risk for planted aquariums — LED, T5HO, and T8 fixtures with depth attenuation and plant demand bands.

Aquarium Tank Volume Calculator — Sizing

Aquarium volume in litres and US gallons for rectangular, bowfront, and cylinder tanks — net volume, water weight, and stand load planning.

Aquarium Salt Mix Calculator — Brackish & SG

Calculate salt mass for target specific gravity in brackish aquariums — species SG for mollies, puffers, and gobies plus water-change cost in USD or GBP.