Free aquarium tools
Three small calculators we kept reaching for. The same math the in-app forecast runs on — only here, you don't have to log anything.
CO₂ calculator
Enter pH and KH, get CO₂ in mg/L. The pH + KH method, without a dropchecker.
Dosing calculator
How many millilitres of your fertiliser get you from current to target? Tank volume in, dose out.
Water-change impact
What does a 30% water change actually do to your nitrate? Or your KH? Mass balance, no spreadsheet.
Hardness converter
dKH ↔ ppm CaCO₃ ↔ meq/L, and dGH split into Ca + Mg. The unit translator for every test kit you'll meet.
Nitrogen cycle timeline
Watch NH₄ → NO₂ → NO₃ over the weeks of a new tank, with sliders for tank size and ammonia source. The chart you wish your fish-in-cycle came with.