How deep should aquarium substrate be?

Most reef tanks use 1 to 2 inches of sand. Shallow beds are easier to clean, while a 2 inch bed gives wrasses and burrowing animals more natural cover. Deep sand beds of 4 inches or more should be planned carefully because they trap more nutrients and are harder to move later.

Is live sand heavier than dry sand?

Yes. Packaged live sand usually weighs more per cubic foot because it includes moisture. Dry aragonite is a good planning default near 90 pounds per cubic foot, while wet live sand is closer to 95 pounds per cubic foot.

How many bags of sand for a 75 gallon aquarium?

A standard 75 gallon aquarium is usually 48 x 18 inches. At 1 inch deep it needs about 45 pounds of dry aragonite sand. At 2 inches deep it needs about 90 pounds, or five 20 pound bags.

Should I rinse aquarium substrate before adding it?

Rinse dry sand and gravel until the water runs mostly clear to reduce cloudiness. Do not aggressively rinse packaged live sand if you want to preserve the bacteria and fine suspended material that came with it.

Aquarium Substrate Calculator

An aquarium substrate calculator estimates how many pounds of sand, gravel, aragonite, or planted substrate you need from tank length, width, target bed depth, and substrate density. Use it before buying bags so your sand bed comes out even.

Planning a new reef setup? Save the calculation with your tank notes in My Reef Log.Start a free reef log

Tank Footprint

Measure the inside length and width where substrate will sit.

Tank Length (in)

Tank Width (in)

Desired Bed Depth (in)

Substrate Type

Pick the closest material, then adjust bag size and price.

Custom Density (lb/ft3)

Bag Size (lb)

Price Per Bag (optional)

Good default for reef sand from 0.5-2 mm grain size.

Result

90 lb of substrate

Weight

90 lb

Metric Weight

40.8 kg

Substrate Volume

1 ft3

28.3 L

Bags to Buy

5 bags

20 lb each

Estimated purchase cost

$160

Printable reef keeping worksheets

Keep a clean backup log for test day.

The Printable Reef Logbook gives you water testing, dosing, maintenance, and livestock worksheets you can print or save as a PDF.

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Aquarium Substrate FAQ

How much substrate do I need for an aquarium?

Measure length and width, choose the bed depth, then convert that volume into weight using the substrate density. The calculator handles those conversions and rounds up to full bags.

How deep should a reef tank sand bed be?

Most reef tanks use 1 to 2 inches. A shallow 1 inch bed is easier to clean, while a 2 inch bed looks fuller and gives sand-sleeping fish and burrowers more room.

What density should I use for aragonite sand?

Use about 90 pounds per cubic foot for dry aragonite sand. Wet live sand is usually a little heavier, so the calculator uses 95 pounds per cubic foot for that preset.

Why does the calculator round bags up?

Substrate is sold in whole bags, and aquascaping often uses a little more than the math predicts. Rounding up helps avoid a thin corner or a second store trip.