Why this number
Nominal volume is L×W×H. Usable water is lower once substrate (and later décor) displace space. Dose fertilizers, CO₂ bubble rates, and stocking math from the usable number when you can.
How to use
- Measure internal centimeters.
- Enter substrate depth (0 if bare bottom).
- Use net liters for dosing and water-change % tools.
FAQ
Manufacturer gallons differ?
Brands often round or quote external sizes. Measure water yourself when precision matters.
Do rocks reduce volume a lot?
Yes on heavy hardscape — subtract a rough % if the scape is dense.