Aquarium volume and substrate calculator
Enter the inner dimensions of the tank in cm, the substrate height at the front and back and a hardscape estimate. You get the gross volume, the actual water volume and litres of substrate.
Gross volume and actual water
Gross volume is length × depth × height. There is less actual water: substrate, rocks and wood usually take 15–30 % and the water line sits a centimetre or two below the rim. Dose fertilizers and treatments by the actual water, not the volume on the box.
Substrate for a slope
A slope from the front glass to the back adds depth to the layout. Typically 2–4 cm at the front and 6–10 cm at the back. The calculator assumes an even slope, i.e. the average of the front and back height.
Aquasoil settles a little once flooded, and hills behind rocks use more than the formula shows. One spare bag is worth having.
Estimating hardscape
A few stones and a small piece of wood take about 5–10 % of the space above the substrate. An iwagumi with large stones or a dense wood build 15–25 %. You find the exact figure by counting buckets when you first fill the tank.
More tools
- Aquarium CO₂ calculator from KH and pHWork out the CO₂ level in your aquarium from KH and pH or from the pH drop against degassed water. With notes on when the formula fails.
- Nitrate and water change calculatorWork out where NO₃ in your aquarium settles with your water changes, how it develops week by week and what percentage to change to keep nitrate on target.
Guides
- Cycling a planted aquarium: the first weeks and when to add fishHow long cycling a planted tank takes, what to test, how often to change water with aquasoil and when it is safe to add shrimp and fish.
- Aquarium water changes: how often and how muchHow much water to change in a planted aquarium, how often, what to watch with temperature and chlorine and how to combine it with trimming and cleaning.
- Algae in a new aquarium: which are normal and what to doBrown diatoms, hair algae and green dust in a new planted aquarium. Why they appear, which go away on their own and what helps without chemicals.
- Fertilizing a planted aquarium: macros, micros and target levelsWhat aquarium plants need, guideline levels for NO₃, PO₄, K and Fe, the difference between EI and lean dosing and how to spot a deficiency.