How Much Live Sand Per Gallon For Saltwater Tanks?

When setting up a new saltwater tank, part of the planning involved is deciding on how much live sand or other types of substrate you are going to use. 

This can be somewhat confusing as every tank is different in size and purchasing the right amount of sand is important.

You don’t want to buy too much sand or not enough to cover the bottom of your tank properly. 

Some people may decide to not use live sand and go with a simple bare bottom saltwater tank.

If you choose to use live sand, you will have to pick between a shallow sand bed or a deep sand bed. 

Regardless of which one you decide to go with, you will need to know exactly how much live sand to use in the tank.

In this article, I will show you how much live sand per gallon you should use in your saltwater tank.


How much live sand per gallon?

If your goal is to use a shallow sandbed, you should aim to have around 1.5-2” sand depth or 1-1.5 pounds of live sand per gallon tank size. 

If your goal is to have a deep sandbed, you should aim to have around 6” depth. 


Shallow sandbed vs deep sandbed – Pros and cons

If you are looking to have a nice sandbed in your tank that is visually appealing, you can use a shallow sandbed.

There is no set rule for the amount of sand to use, you can choose the amount that looks the best for your tank.

As a general rule of thumb, most people will use 1.5-2” sand depth for a shallow sandbed.

If you are looking to use a deep sandbed, then you will need to use quite a bit more live sand.

Around 6” depth will be needed.

A deep sandbed is used for denitrification purposes. The idea with deep sandbeds is to prevent oxygen from getting into the bottom layer of sand.

Bacteria will remove nitrates naturally from the water that live in the oxygen-free zones of the sand.

Pro tip: Avoid using a deep sandbed in shallow tanks. If your tank is only 18” tall, a sandbed of 6” or more would cover the bottom half of your tank. 

It is crucial to avoid using live sand at a depth that is in the “danger” zone. This is between 2” and 6”. You should have less than 2” or 6”+.

Toxic gas can be released and wipe out your tank quickly if you are not careful. You don’t want the sandbed being stirred up releasing toxic gas from the anaerobic part of the sandbed into your tank. 

shallow sandbed vs deep sandbed

Shallow sandbed 


  • Visually appealing
  • Best for sand sifting fish
  • Cheaper to purchase
  • Easy to clean
  • Will not clog due to detritus
  • Beneficial bacteria surface area


  • Sand will blow around the tank easier

Deep sandbed


  • Denitrification
  • Supports rocks and protects the glass


  • More sand required – heavier
  • More expensive to purchase
  • Takes up more space in the tank
  • Stagnant deep sandbed can release toxic gas

can you use ocean water in saltwater tanks?

How much live sand for a 55-gallon reef tank?

If you have a standard 55-gallon aquarium, it will have the dimensions of 48” L x 13 W”. You should use around 55 pounds of live sand and plan to cover the bottom of the tank with 1.5-2”. 

What’s the difference between live sand and dry sand?

Live sand is considered to be any sand used in saltwater tanks that is colonized by bacteria and organisms. This helps with the removal of organic waste and is important for the overall biodiversity of a saltwater aquarium.

When you purchase live sand for your aquarium, it will most likely be packaged with saltwater and live bacteria which is healthy to use in your tank.

Using live sand such as Carib sea Arag alive will help with the cycle of the tank when new and create a natural biological balance.

It also reduces the “new tank syndrome” and helps reduce nuisance algae. 


Did you know? 1 grain of sand can contain up to 100,000 microorganisms and thousands of species!


Dry sand contains no bacteria or living organisms. It’s just sand that is dry and therefore doesn’t have the benefit of helping the tank cycle faster or create a biological balance when the tank is new.

Over time, dry sand will become live and become an important part of your tank’s biodiversity. 


Aquarium Live sand calculator

If you are looking to find out how much sand you need for your tank, check out this sandbed calculator on Marine Depot. It works with all tank sizes and shapes and will calculate the amount of sand you should use. 


Best live sand for saltwater tanks

There are many different types of live sand to choose from. You can choose fine or coarse sand depending on the look you want.

Also, consider the livestock in the tank and the amount of water movement as these are factors to consider before deciding which type of sand to go with.

Caribsea Arag Alive Fiji pink

One of the most popular choices for live sand, Fiji Pink is fine sand that looks very natural and clean. It is perfect for sand sifting fish and invertebrates.

It is ready to be used right out of the bag, do not rinse live sand. 

Check today’s price of Caribsea Fiji Pink live sand on Amazon here.


Caribsea Arag Alive Special Grade

Caribsea Special grade sand is coarse sand that has a larger grain size and can be used in tanks with higher water flow. It does not blow around the tank like some finer sands.

This sand can also be used right out of the bag with no rinsing. 

The Caribsea Arag Alive Fiji Pink and Special Grade come packed with millions of beneficial bacteria to enhance biological filtration.

Check today’s price of the Caribsea Special Grade live sand on Amazon here.



Regardless of the type of live sand you decide to use, it’s important to choose the right amount to suit your tank. If you are using a shallow sandbed, plan to have around 1.5-2” depth in your tank or around 1-1.5 pounds per gallon. Deep sandbeds should be at least 6” deep for denitrification purposes. There are pros and cons of each so choose your sand depth wisely!

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5 Best corals you can put on the sandbed