Tools

A free tool for every part of the tank.

Instant, no-signup calculators and lookups — grouped so you find the right one fast. No account, no ads, all free.

Water chemistry & CO₂3 tools

CO₂ cylinder runtime estimator

Days remaining, run-out date and reorder reminder from weight, bubble rate and diffuser type.

Drop checker colour guide

Personalised colour reference by KH — the exact shade your checker should show at each CO₂ level.

Fertiliser comparison calculator

Compare branded fertilisers side by side — the NPK and micros each delivers in ppm, at the maker’s dose or your own.

Planning & hardware5 tools

Tank Kit Builder

Answer four quick questions and get a recommended equipment checklist — filter, heater, substrate, CO₂, lighting and testing, sized to your tank.

Tank volume calculator

Any shape — rectangle, bowfront, hex, corner, cylinder or sphere. Adjusts for fill level, substrate and hardscape.

Substrate calculator

Volume, weight and bag count for ADA, Tropica, Fluval Stratum, UNS Controsoil and more. Flat and sloped layouts.

Filter capacity calculator

Biological surface area and maximum fish load by media type. Based on aquariumscience.org data.

UK shops & suppliers map

A community map of recommended UK aquarium shops, plant & hardscape stockists, CO₂ refills and breeders — search, filter and get directions.

Species & biology2 tools

Fish species lookup

Temperature, pH, hardness, max size and tank requirements for 180+ commonly kept aquarium species.

Plant species lookup

Light level, CO₂ requirement, water parameters, growth rate and placement for 140+ aquarium plants.

Tracking & logging3 tools

Log water test results for any parameter — nitrate, pH, ammonia and more — and view them as graphs over time.

Maintenance schedule

Plan a full routine for every tank — water changes, dosing, filter cleaning and testing — on a visual calendar, saved to your account.

Aquarium heat forecast

14-day temperature forecast with Good / Warming / Extreme risk indicators for your location.

Also in My Tank

Four more tools live inside My Tank, tied to your saved tank profile — still free, and no account needed to start: a real-time pH Monitor for CO₂ tracking, an RO water mixer, a fertiliser dosing calculator and a water change planner. That’s seventeen tools in all.

Why we built these tools

Every calculator and lookup on this page is free, runs entirely in your browser, and needs no account, email or download. Nothing you type is sent to a server — the maths happens on your device, and your numbers stay with you.

The aim is not to replace your own judgement but to take the arithmetic and guesswork out of the fiddly parts — fertiliser dosing, CO₂ runtime, true water volume, stocking limits. Where the underlying science is settled we lean on it and cite it in the guides below; where the hobby runs on rules of thumb, we say so rather than dress it up as established fact.

The science behind the tools