Hi Reefers, today we are going to dig into the topic of sand. One of the most common questions we get is “should I go with a bare bottom tank or have a sand bed? Although it's not for everyone, some reefers really prefer bare bottom tanks as they are much easier to keep clean.

By removing substrate, contaminants are far more likely to stay in the water column where it is removed by your mechanical filtration.. Anything that does settle can easily be siphoned out as well. Just like with your other bare glass surfaces, algae will accumulate over time and the bottom will need to scraped clean. Despite its benefits, bare bottom tanks just don’t appeal to everyone.

Thankfully, over the years manufacturers recognized the demand for much more natural looking marine sands. Now, we have more options than most of us know what to do with. Many people prefer to go with a sandy bottom for their tank as it adds a new dimension and makes it more reminiscent of the actual ocean floor. However, most first time aquarists overlook the “live sand” aspect of these substrates.

Similar to live rock, sand grains can host a variety of marine life including bacteria. These microscopic organisms are what make the sand “live.” For a long time, it was thought that a tank’s population of beneficial bacteria were housed in and on live rock. After all, that is where nitrification and denitrification take place. A recent study by the Max Planck Institute actually revealed that a single grain of sand can be home to 100,000 microorganisms. Much more than previously believed.

Although the surface of the sand bed is constantly scrubbed free of microbes, the cracks and crevices just beneath the surface are home to a diverse population of bacteria that filter your tank.

As your tank matures, your sand will mature too, by developing a unique mix of microbes. These microbes are cable of recycling nutrients such as carbon, phosphorus and nitrogen. It will also support tiny inverts that will sift through sand, looking to make a meal of them.

If you want to create your live sand bed, there is a wide variety of sands to choose from. Here's some of the basics that you may need to know when making a choice.

Marine sand comes in two forms: Dry and Live. Dry sand is simply natural aragonite substrate that is screened to a specific size. CaribSea’s Aragamax Sugar-sized sand comes in a particle range of 0.25 to 1 mm. The fine sand creates a silky-smooth substrate-perfect for sand-sifting gobies and crabs. Keep in mind that strong water flow will probably resuspend the fine sand particles. Strong currents can push the sand around, eventually exposing the glass bottom of the aquarium. Fine sand is best used in tanks with lower flow rates.

Aragamax Select is screened to .5 to 1 mm. It’s a little larger than sugar sand. It can still be sifted by gobies and is a bit less prone to blowing around.

For most reef tanks with strong water flow, we recommend CaribSea’s Special Grade Reef sand. The 1 to 2 mm particle size creates a nice look in the tank and won’t resuspend like finer sands. This reef sand will stay put and, unlike fine sands, it won’t grind in the bearings of flow pumps.

You can even blend in a large-grained substrate, like Aruba Puka Shell, if that’s the look you want. Jawfish and blennies like to use the shells to construct hiding areas.

Live sand products are simply just your standard dry sand that has been inoculated with bacteria culture. The idea is to add bacteria to help jump-start the bio filtration, rather than letting it slowly develop on its own. Arag-Alive comes in a variety of sizes and colors like Fiji pink, Hawaiian black and traditional white aragonite.

CaribSea’s Ocean Direct line of sand comes damp in a special breathable bag. Each sand grain is coated with its original bacteria. The damp live sand can breathe through a thin film of water that surrounds each particle. CaribSea says Ocean Direct sand contains up to 1000 times more live bacteria that other sand preservation method. Ocean Direct is available as a fine oolite sand or original grade that ranges from 0.25 to 6.5 mm.

Once you select the particle size and color, it’s time to calculate how much sand you’ll need. We’ve made it easy. Just use our Sand Bed Calculator linked in the cards. It works like this. All you have to do is plug in the length and width of your tank. The calculator has many options including curved, hex and custom aquariums. The final step is to select the density of the sand you want to use. Sand densities are listed with every sand product description. Now hit Calculate button and see how much sand you’ll need. It’s that simple.

When placing live rock, it is often best to set it directly on the bottom of the tank and add the sand after words. Doing this will prevent the rocks from shifting as the sand gets excavated by fish and inverts.