Tank calculator
How much water is really in there?
Almost nobody doses for the right volume. A tank never holds what the label says — the substrate, the rocks and the gap below the rim all take their share, and dosing for the label is how fish get overdosed.
Common sizes
Tank size
Tank volume
154 L
Actual water
123 L
This is the number to dose against
25% water change
30.8 L
How much do I add?
Read the rate off your bottle and put it in — every brand is different, so we won't guess it for you.
ml perlitres
For the whole tank
61.6 ml
For a 25% change
15.4 ml