live sand and starfish

What is live sand?

A new saltwater aquarium is a somewhat sterile, harsh environment for those first few animals to colonize. As a result, some of those first fish and invertebrates we add to our tanks don’t survive. It can be challenging to nail down exactly what this new tank syndrome is, but the bottom line is that it can take a little time to build the base for success in a new saltwater aquarium–and one important part of the equation is establishing colonies of the beneficial bacteria and invertebrates in our tanks. Live sand can be a major factor in that equation.

Live sand

In the ocean, the sand bed is home to an amazing diversity of living things. In a mature saltwater aquarium, lots of things live on, around and in the sand bed, too. Microscopic bacteria and tiny invertebrates call the sand home and have an important role in keeping your aquarium system balanced.

Some of the bacteria that colonize your sand serve as the backbone of your biological filter. In the freshwater aquarium hobby, some people use hang-on-back filters where the bacteria colonize a sponge or biowheel or sumps with bioballs, etc. By comparison, natural substrates, like live rock and live sand are much more common in the saltwater aquarium hobby. The surfaces of the rock and sand become coated with pollutant-filtering bacteria that help you to keep your tank water in livable condition.


live sand and starfish

So what is live sand?

Live sand, the concept

Conceptually speaking, live sand is any sand that is colonized by bacteria and invertebrates that adds to the biodiversity of a saltwater aquarium. If we compare the saltwater aquarium to the human body, the sand is like an organ (eg. kidneys) removes pollutants from the water and replaces them with less toxic chemicals the body (your tank) can better manage.

Live sand is a habitat that helps grow a tiny invertebrate clean-up crew. Bristle worms, tiny starfish and copepods/amphipods will all live on and around your live sand bed. Each of these creatures plays an important role to help you keep your tank clean of extra food and waste.

Live sand, the product you buy

It is also the name of a specific type of sand you would buy online or at your local fish store.

This sand is packaged in saltwater along with the bacteria and invertebrates living among the sand. The sand isn’t alive, but they are thought to be biologically active, meaning they already harbor living populations of ‘the good stuff’ you want in your tank.

The case for buying live sand

Buying and adding live sand to your tank is a simple way to add biodiversity to your tank. A new saltwater tank can be a harsh environment to adapt to because the water is relatively devoid of life–after all, you just set the tank up.

In addition to the general thought of increasing your biodiversity, there is a very practical reason to add live sand to your new saltwater aquarium

Do I need to add live sand to my tank?

No, you don’t need to add live sand to your tank. In fact, many people don’t have sand in their tanks at all, preferring a bare bottom tank instead.

All sand will become live sand in your tank, once it matures. Live sand can be much more expensive than dry sand. The bags are smaller, partially filled with water (instead of with more sand) and they can be fairly expensive. You can just add (washed) dry sand to your tank. Check the label to be sure the sand isn’t treated with any chemicals.

all sand live sand
All sand eventually becomes “live sand” in your tank. Check out all the living things in the sand from this tank at a public aquarium

You will need to jump-start your biological filter somehow, but as long as you are also adding live rock or some other bacterial/invertebrate ‘boost’ culture to your tank, your regular old sand will become live sand in time or you can skip adding sand altogether.

My recommendation

A cost-minimizing strategy to fill your tank with (live) sand

If you are just starting out your saltwater aquarium and you are on a budget, I don’t recommend that you fill your tank with live sand. That would be expensive. Instead, you can achieve similar results (just a little bit slower) by adding a relatively small amount of live sand to a bulk of regular sand in your tank.

Once you decide how much sand you want to have in your saltwater aquarium, buy a little bit less than the total amount you need of regular dry sand and supplement with a bag or two of live sand. This way you can afford to cover your tank with the amount of sand you want (instead of the amount of sand you can afford) and the living creatures in the live sand will quickly colonize the sand bed converting that non-living sand into live sand in no time.

Live sand products

The big name in live sand is CaribSea. They offer a mind-numbing array of options. How do you choose the best one? Believe it or not, the most important strategy for picking the right sand/substrate (in my humble opinion) is to pick the one you like the most–in terms of how you want your aquarium to look.

If you plan to keep specific animals that will burrow in your sand, you want to take notice of the type of sand they prefer (for example, some species need a mixture of fine and coarse grains to build their homes), but in the absence of having specific needs from specific animals–the truth about sand is that you should pick the chemical-free substrate that you think looks the best.

I wrote more about the truth about aquarium sand in another article because there is some misinformation out there about the role of sand in maintaining pH control.






2 responses to “What is live sand?”

  1. Kym

    Not on topic but hoping you could comment/blog about LED lights. I hope to set up a new tank (red sea reefer) and i will need lights. Any direction is appreciated.

    1. Hi Kym, thanks for the comment. I’ll send you an email.

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