Calculator
Tank and pot volume, gallons, liters and bags of soil.
The water a tank holds, what it weighs full, and the substrate to fill a tank, a pot or a tray to a given depth.
The container
Shape
Units
in
in
in
in
What goes in
in
in
in
Holds
-
In liters-
Water in it, at the fill line-
That water weighs-
Substrate for the depth set-
Drainage layer-
Substrate weighs about-
Nominal tank sizes are generous: a "10 gallon" glass tank holds about 9 gallons to the rim and less with substrate and a lid. Trust the measurements, not the label.
How it is worked out
A box is length × width × height; a round pot is π × (diameter / 2)² × height, which treats a tapered pot as a cylinder of its top diameter and overstates it a little. One US gallon is 231 cubic inches or 3.785 liters; a liter of water weighs a kilogram, a gallon 8.34 pounds.
Buying substrate
- Potting mix and coir are sold by volume: a small bag is 8 dry quarts (about 8.8 liters), a large one 1 to 2 cubic feet (28 to 57 liters). Coir bricks expand to roughly 8 to 9 liters each.
- Aquarium sand and gravel are sold by weight. A liter of dry sand or fine gravel weighs about 1.5 kg (a gallon about 12.5 lb); the calculator uses that figure, so a 1-inch sand bed in a 10-gallon tank is about 10 lb of sand.
- A terrarium drainage layer of clay balls (LECA) is far lighter, about 0.35 kg per liter.
- Microgreen trays: a standard 10 by 20 inch tray at 1 inch of coir takes about 3 liters, so a brick fills three trays.
Weight on the furniture
Water is heavy. A 20-gallon tank is 167 lb of water before the glass, the substrate and the rock, and a 40-gallon breeder passes 400 lb. Desks and ordinary bookshelves are not built for that; a purpose-made stand, or a floor against a wall, is.
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