Aquarium math, done right
Real water volume, water change planning, toxic ammonia from your test kit, and label doses scaled to your tank.
Numbers worth knowing
- 231 cubic inches = 1 U.S. gallon
- Nitrite can harm fish from 0.10 mg/L (UF/IFAS)
- Un-ionized ammonia above 0.05 mg/L can damage fish tissue
- New biofilters take about 6–8 weeks to establish
Calculators
CalculatorAmmonia toxicity calculatorToxic NH3 from your test reading, pH and temperature.CalculatorAquarium dosing calculatorLabel dose scaled to your real water volume.CalculatorAquarium volume calculatorReal gallons and liters after substrate and fill gap.CalculatorWater change calculatorPercent to change to hit a nitrate target.
How we work
Measure, then calculate
Every tool starts from something you can measure: tank dimensions, a test kit reading, a label rate.
Sources on every page
Thresholds come from university extension and EPA publications, linked below each tool.
Labels first
For treatments and medications, the product label is the authority. We only do the scaling.
Guides
GuideThe nitrogen cycleHow bacteria turn ammonia into nitrate, and how long it takes.GuideWater changesSize and frequency from your readings, plus a safe routine.GuideTreating tap waterChlorine vs chloramine and how to treat tap water.GuideTesting aquarium waterWhat to test, how often, and what readings mean.
New to the terms? Our glossary explains them in plain words.