The Grainy Truth About Aquarium Sand – Ultimate Reef Tank Sand Guide.

A few weeks ago, I was at a lunch with a small group of friends. As we rounded out our meal and enjoyed a cup of coffee, the topic shifted to aquariums (I know, a big surprise, right?). While most of us have been reefers for years, a friend-of-a-friend, Clementine, listened on with a specific look of confusion.

There we were, going on about flow pumps and the latest news when I looked over at poor Clementine. Like a fish out of water, her face morphed into what I can only describe as a question mark. As soon as there was a lull in the conversation, her delightful southern accent pierced the air, “So, wait, there’s different types of sand? I always thought it was just, you know, sand.”

The Sandy Shores of Your Microcosm - Natural Reef Sediments.

Regardless of your preferred style, maintenance techniques or care tactics, our ultimate goal as reefers is to master the art of replication. From water circulation, to nutrient parameters, failure to achieve a realistic ecosystem results in lackluster growth, or worse, a complete tank crash.

To fully grasp the importance of sand, you must first understand its role in the wild. While I won’t dive into great detail, I feel there are several key points worth noting.

Here’s a question: Are coral reefs animal and plant made structures?

If you answered yes, you aren’t technically wrong. But, as with almost every reefing topic, you’re only partially correct.

Essentially, corals comprise only a small percentage of the entire reef. If this is true, then what’s the rest of a reef system made of? Surprisingly, the bulk of every naturally formed reef ecosystem is primarily made of sediment. The extent of sediment is so great, many experts feel reef systems are more accurately described as being an expansive sedimentary rock.

In the wild, sediment in reef systems are composed of a variety of substances. The exact composition is determined by the biologic and geological composition of the local environment. Generally, sediment may be a collection of three different aquarium substrate types, which include:

• Unconsolidated Sediment - Defined as individual particles with diameters measuring anywhere from 1/16th to 2 millimeters.
• Gravel - As you may already know, gravel is a much more coarse version of sand and is composed of larger particles. 
• Silt - Out of the other two primary categories, silt is made of very fine particles. These items tend to be so fine, its texture feels slippery. In some cases, it almost feels like slime.

Of course, this is only the physical characteristics of select sediment variations. As you dive deeper into the unique landscapes of reef system sand beds, you’ll uncover even greater insights into this grainy realm. The substances that make up reef sediment varies based on its natural environment. For example, coral found near the mouth of a river tend to demonstrate silica sands, while reef systems near volcanic islands tend to be composed of mainly lava sand.

While this is all very interesting, what does it have to do with your reef aquarium? Well, surprisingly, a lot.

Even though your tank is a closed, manmade environment, the type of aquarium substrate used is just as important as the quality of water flow or nutrient supplements. As you cultivate your tank, and begin cultivating coral, sand type must be similar to the version the coral would experience in the wild.

Not only does this play a biologic role, which we’ll discuss momentarily, but incorrect sand varieties can cause serious issues. For example, since SPS coral thrive in high flow, turbulent waters, lighter, finely grained sand would constantly be shifted and moved around due to such strong currents. As you can imagine, this can result in unsavory results.

Much like in the wild, achieving the pinnacle of health and vitality within your aquarium requires all components to work with each other. In many ways, the root of all reef tanks is the quality of homeostasis, which is to say, how well each individual part interacts with all others.

The Shifting Sands of Tank Perfection - Dry Sand vs Live Sand.

Now that we’ve briefly discussed the role and variations of sand in the wild, and how this connects to your reef tank, it’s time to get into the gritty topic of aquarium sand types.

While there is a wide array of options, there are two primary aquarium substrate versions that require explanation: live sand and dry sand.

Much like live and dry rocks, these sand variations offer their own unique advantages and disadvantages. While the “best” option for you comes down to your personal preferences, there are several hallmark qualities worth discussing.

It’s Alive! A Brief Overview of Live Sand.

Essentially, live sand is just that, it’s alive with billions of organisms and bacteria. I know what you may be thinking, “Why would you want to intentionally place bacteria in your tank?!”

As I’m sure you remember from school, not all bacteria is bad. In fact, our very existence relies on the beneficial action of “good” bacteria. The same is true for your reef tank. Without specific bacterium, and other helpful microscopic organisms, it would be impossible to sustain a healthy aquarium.

In brief, live sand offers a streamlined way to maintain tank health. Rather than populate your tank with bacteria and organisms, live sand does the work for you.

Essentially, as a responsible reefer, you should weigh the pros and cons of live sand. If you decide to go this route, use live sand from a reputable supplier, such as CaribSea Arag-Alive.

The Dryness of Easy Beauty - Dry Sand.

As I’m sure you can already determine, unlike live sand, dry aragonite sand doesn’t come with a legion of bacteria ready to populate your tank. Instead, this version is void of any living organisms, which is ideal when cycling your new reef tank or refilling a pre-established tank with new sand.

Perhaps the most important topic to discuss when dealing with dry sand is its composition. Generally, avoid silica-based sand. While not true for all brands, this variety is notorious for having excess free silicates, which can result in continuous diatom problems. If you aren’t aware, diatoms are a form of brown algae that’s common in almost every reef tank. However, you shouldn’t actively encourage their population.

In my opinion, which is also shared by most reefers, aragonite sand is the preferred composition. Along with having a low silica rating, this variety looks absolutely stunning in a reef aquarium. Its appearance looks surprisingly natural, which is an aesthetic bonus!

• Aragamax Sugar-Sized Sand - This is the smallest/finest sand offering with a diameter of 0.25 to 1.0mm. This variety should only be used in low flow tanks, such as one housing LPS coral.

• Special Grade Reef Sand - Measuring 1.0 to 2.0mm in diameter, this is a pretty standard looking sand type.

• Aragamax Select - With a diameter of 0.5 to 1.5mm, the granular appearance of this type is finer than the Special Grade, but not as fine as the Sugar-Sized Sand.

• SeaFlor Flamingo Reef - Without a doubt, this is my personal favorite, and is used in most of the Reef Hacks aquariums. Its appearance is surprisingly lifelike and features a variety of natural colors. Its size is appropriate for a variety of uses with a diameter of 1.0 to 2.0mm.

• Fiji Pink - This relatively small sand, which features a diameter between 0.5 to 1.5mm, offers a more granular appearance without a “chunky” look.

• SeaFlor Super Reef - If you enjoy a more “natural” appearance, then this type may be what you’re looking for. Unlike the Flamingo Reef, this sand variety offers uniform coloration and a much broader combination of granular sizes, which measure from 0.5 to 2.5mm in diameter.

Regardless of supplier, or sand size, you should always prepare the sand before placing it in your tank. I prefer to thoroughly soak dry sand in RO/DI water for a period of 24 hours. During this time, change the water at least seven times. Before changing the water, give the bucket a through shake each time to help remove as much dust particles and any other undesirable elements.

The Great Depth Debate - Sand Bed Thickness, Deep Sand Bed vs Shallow Sand Bed.

Before closing out, there’s one last element we must discuss: sand bed depth. If you spend any time browsing reef aquarist forums, which I highly recommend doing, you’ll notice a theme.

Some reefers prefer deep sand beds, while others prefer shallow sand beds. So, what’s the best? Well, as I’m sure you’ve already guessed, it really depends on your tank inhabitants. While deep sand beds have its own unique advantages, when it comes to cultivating a thriving ecosystem, I’ve found shallow sand beds deliver far greater results.

The “official” measurement of shallow sand beds is anywhere from 0.5 to 1-inches deep, while deep sand beds feature a depth of 3 to 6-inches deep. While your choice may be somewhat limited based upon reef tank size, does depth really matter? Absolutely!

Essentially, sand bed depth plays a direct role in natural biological filtration. Traditionally, deeper sand beds were recommended as the deeper you go, the less oxygen is present in water. Therefore, bacteria responsible for converting nitrate into nitrogen gas, which are known as anaerobic bacteria, thrives in greater concentration.

However, innovations in reefing have made this traditional guideline obsolete. Rather than taking up precious real estate, risking tank health with hydrogen sulfide pockets and providing ample opportunities for detritus to accumulate, shallow sand beds eliminate these threats.

One major consideration you’ll see repeated by deep sand bed aficionados is bacterial colonization. Since shallow beds feature less overall surface area, it’s said there’s less opportunity for helpful bacteria to grow. While this is true, it’s not the final say.

Media options, such as the BrightwellAquatis XPORT Bio Brick provides 100,000 square feet of bacterial colonization surface area, its equivalent of one New York City block or 1.5 times bigger than the White House! Brick is placed in the sump and provide ample aerobic and anaerobic bacteria growth.

The Shores of Brilliant Tank Health - Final Thoughts.

There you have it. While this is only a brief overview of reef tank sand, you now understand the most essential aspects of this important topic.

Whether you’re just starting out, or are looking to revamp your current aquarium, the entire Reef Hacks team is here for you. Regardless of your experience, we’re here to answer any questions you may have. Simply head over to our Facebook page and send us a message.

Even though this hobby may seem complex, it becomes far easier to manage when you realize you aren’t alone. Together, we can create the reef tank of your dreams! All that’s required of you is patience and a willingness to learn. As always, Reef Hacks is delighted to assist you in any way possible. Happy Reefing!

by Yuliya Ivanova for ReefHacks.

Websites: CaribSea / BrightwellAquatis