Setup & Sizing
Sand Calculator
Work out how much sand, gravel or aquasoil you need, in kilograms, for a given substrate depth. Works from tank footprint or tank volume.
Sand Calculator
Typical: 3 cm for non-planted, 5-8 cm for planted.
Fine sand ~1.6. Gravel ~1.5. Aquasoil ~0.8. Check the bag.
Weight to buy
11.5kg
- Volume
- 7.2 L
- Density used
- 1.6 kg/L
How much sand for a fish tank?
The maths is simple: work out the volume of substrate (length x width x depth), then multiply by the density of the material you're using to turn litres into kilograms.
Formula:
- Substrate volume (L) = (length cm x width cm x depth cm) / 1000
- Weight (kg) = volume (L) x density (kg/L)
Worked example
A 60 x 30 cm base with 5 cm of fine sand is 60 x 30 x 5 = 9,000 cm3 = 9 litres. At 1.6 kg/L that is 14.4 kg of sand. Round up to a 15 kg bag.
Tips
Always buy 10-15% extra. Some will wash down the drain during rinsing, and you'll want spare for topping up low spots after aquascaping. For planted tanks, consider a thinner nutrient layer under an inert cap - that's cheaper than filling the whole bed with aquasoil.
Frequently asked questions
How deep should my substrate be?
2-3 cm is plenty for a non-planted tank (easier to keep clean). Low-light plants and most stem plants want 4-5 cm. Heavily planted tanks with root-feeders like swords or crypts appreciate 5-8 cm, and dirted / aquasoil setups commonly run 6-10 cm with a cap.
What density should I use for my substrate?
Fine aquarium sand is typically 1.5-1.7 kg per litre. Coarse gravel is 1.4-1.6. Aquasoil like ADA Amazonia or Tropica Aquarium Soil is lighter at 0.6-0.9 kg per litre because it's baked clay, not mineral sand. Always check the bag - manufacturers publish this figure on the product page.
Should I rinse the sand before adding it?
Unless it's a pre-washed inert sand, yes - heavily. Rinse in a bucket until the water runs clear. Unrinsed play sand will cloud the tank for days. Aquasoils are the exception and should not be rinsed.
Will sand hurt my fish?
Only sharp-grained sand can abrade fish that like to dig, like Corydoras and loaches. Use "soft" or "smooth" silica or silver sand for bottom-dwellers. Builders' sand is too sharp; play sand is usually fine but rinses forever.
Related calculators
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Lighting
Recommended lighting power in watts or lumens per litre for low, medium and high tech planted tanks.