Aquarium inputs
Aquarium water-change calculator
Calculate the percentage and litres to replace to lower nitrate by dilution.
What it calculates
Formula
(Current nitrate − target) ÷ (current nitrate − replacement-water nitrate) × 100, then applies that percentage to net volume.
Limits
It assumes complete mixing and no new nitrate during the change. It cannot reach a target at or below the replacement water.
Next step
Test both waters with the same method, match temperature and condition replacement water before adding it.