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An integral part of any aquarium is the substrate. For most tanks, your substrate will contribute to your nitrogen cycle and provide a critical component of your overall environment. Depending on what fish and invertebrates you keep, your substrate may be critical to provide housing, feeding and reproductive support. Live sand contains the macro- and microbiota necessary for the health of your reef tank, acting as a biological filter and supporting the well-being of your fish.
Some live sands can also provide pH support by adding in buffering elements, such as calcium carbonate. Found naturally in most reef systems, sand will slowly add buffering to your tank, maintaining a consistent pH.
Live sand comes in a variety of colors and gradients. Which size and color you use is somewhat based on your preference and aesthetic in addition to how your fish and invertebrates will utilize their substrate.
Here are the best live sands for your reef tank.
Best Overall: Nature's Ocean Bio-Activ Live Aragonite Saltwater Aquarium Sand
Best all around for color and weight
Good source of pH-stabilizing aragonite
Sourced from the ocean, harvested sustainably
Can vary in size slightly
This product is sustainably harvested from the ocean and packaged in as close to a natural state as possible. It contains beneficial bacterial colonies, in addition to aragonite, a naturally occurring form of calcium carbonate. This calcium carbonate acts a buffer against changes in your tank's water, promoting a healthy and consistent pH. Meanwhile, the bacterial colonies work to decrease your ammonia and nitrite levels.
It looks great too, with tiny shells added to the mix for a more varied appearance. The sand also settles quickly, with any cloudiness usually dissipating within a few hours.
Nature's Ocean has so much faith in their patented method of harvesting live sand that they guarantee that each pound of their sand contains more than 10 million live bacteria. This rich ecosystem starts working immediately at filtering your tank's water and moving it toward a fish-safe equilibrium. It also provides essential inorganic elements, including cobalt, zinc, and molybdenum, in addition to a variety of trace elements.
Nature's Ocean Bio-Activ Live Aragonite Reef Aquarium Sand comes in several different colors and gradients, to best match your saltwater tank. For example, Natural White #1 has grains between 0.5 and 1.7 millimeters, making it an excellent, uniform choice for most saltwater tanks, including those with bottom-dwelling fish. The White Reef Sand version has a finer grain—between 0.1 and 0.5 millimeters—which is more likely to get kicked up by direct filter and powerhead outflows, but can be a good choice for aquariums with algae eaters that like to pick through sand, such as hermit crabs or snails.
Best Pink: CaribSea Arag-Alive Fiji Pink Aquarium Sand
Appealing color aesthetic
Cycles tank water quickly
Smaller size can cause tank cloudiness
Many saltwater aquarists enjoy the contrast that pink sand provides compared to plain white or natural sand. CaribSea Arag-Alive Fiji Pink Sand is a medium grain at 0.5-1.5 millimeteres, so it is not kicked up easily by filtration and bottom dwellers have an easy time moving it around.
The sand’s microorganisms are engineered to reduce “new tank” syndrome, where ammonia and nitrite levels become dangerously high—a common symptom in environments that haven’t had time to develop the proper levels of bacteria. It also discourages problematic algae growth and never needs to be replaced.
Like most pink sand available on the market, it will have a mix of pigments—including brown, pink and white grains—giving this sand a spectacular appearance in a natural reef environment.
Best Black: Carib Sea ACS00797 Arag Alive Hawaiian Reef
Gives high contrast to vibrantly colored fish and invertebrates
Excellent for low-light tanks
Large grain won't shift around
Harsh aesthetic, not a natural backdrop
For bold contrast, some marine aquarists go with a black substrate. Black sand is great at setting off the color of vibrant corals and marine fish. Darker substrate is recommended specifically when dealing with lower-light species, such as flashlight fishes. It is a starkly different aesthetic from most marine tanks.
The Hawaiian Black Sand from CaribSea also has a larger grain size—between 0.25 and 3.5 millimeters. Combined with its black color, this makes the Hawaiian Black option a little more low maintenance. Grains are large enough they won't swirl around or get sucked into intakes, while the black color won't show algae spotting like white sand does.
Best Fine: Nature's Ocean Bio-Activ Live Aragonite Natural White Reef Aquarium Sand
Best for bottom dwelling fish and inverts
Hardest to keep clean
Can easily cause tank to become cloudy
Fine sand gives an exceptional texture to any reef environment and is great for having lots of bottom-dwelling fish and invertebrates to enjoy. Nature’s Ocean White Reef Sand features grains between 0.1 and 0.5 millimeters.
While fine, white sand can give a clean look to a reef tank, it requires a little more maintenance. Carefully direct filter and powerhead outflows in order to limit substrate drifting. Powerful currents can easily lift fine substrate and it will not settle out, causing a cloudy tank appearance. The hardest part about dealing with white substrate is that it will look “dirty” more frequently than other colors. White grains will quickly pick up algae that will be more noticeable than with tan, pink or black substrates. It is better for tanks with a lower bioload or those that are meticulously cleaned by their owners or the tank’s inhabitants.
Best Coarse: CaribSea Arag-Alive Natural Reef Aquarium Gravel
Best for mixing with lighter sands for weight and contrast
Harder to clean due to weight in siphon
Not suitable for burrowing fish or animals
Ranging in grain size from 3 to 5 millimeters, CaribSea Natural Reef sand is a great natural element to add to any reef tank. It does not get pushed around easily by filtration elements and most bottom dwelling fish and invertebrates do not have trouble relocating it. It is not recommended for fish that require full sand burrows, but can be mixed with smaller grain sand to provide some weight and contrast to the marine environment.
What to Look for in Live Sands for a Reef Tank
While colors are mostly an aesthetic consideration, there are a few scenarios where specific colors have specific strengths and weaknesses. This is most notable with black sand, which is preferred for aquarium tanks with lower-light species because it minimizes light pollution from reflections.
While is another color that warrants extra consideration. While white can provide a tank with a clean, attractive aesthetic, it can also look dirty very easily. White tends to show patches of algae and other impurities, making it a better pick for frequently-maintained tanks, or aquariums with lots of algae-eating creatures to keep the sand clean.
Live sand grains vary in size from 0.25 millimeters up to 5 millimeters. Smaller grains are lighter and easily pushed around by currents, which can cause tanks to be cloudy. Larger grains can be harder for bottom-dwelling fish and invertebrates to work with and are harder to clean in a siphon.
Sand can be slightly trickier to clean than larger, heavier substrate, such as gravel and rocks. In tanks with fast-moving water, be sure to angle powerheads and filter returns so they do not continually kick up sand. Agitated sand can easily get into filters and clog motors, causing pump burnout or failure. If you continue to have issues with sand clogs, you may try lowering your sand level or redirecting your filtration components.
“Live” sand contains microscopic bacteria that work to benefit your tank’s environment. Like those that live in your other biological filtration components, such as filters and fluidized beds, these are “good” bacteria that break down nitrogenous wastes and convert them into less toxic compounds. They are microscopic and can live in various places throughout your aquarium. Pay close attention to any expiration dates printed on bags of live sand! Do not use it in your system if the product has expired.
How does live sand prevent “New Tank Syndrome?”
“Live” sand, provided it has not expired, contains beneficial bacteria that help run your nitrogen cycle. These bacteria convert fish’s primary waste product of ammonia into safer compounds of nitrite and nitrate. Some colonies may even contain bacteria that can sequester nitrate, decreasing the amount of water changes your system will require.
Do I have to use live sand for my saltwater tank?
Absolutely not! If your tank is already established and cycled, you do not need to increase your bacteria load by adding live products. Other live cultures, such as live rock, can help boost your beneficial bacterial colonies. Even if you are starting a brand new system, starting with a low bioload, or just a few fish, can start to cycle your tank gradually. As your cycle is established, you can start to add more animals to your tank.
How do you determine how much sand your tank needs?
Many manufacturers will recommend a certain amount of sand per gallon of water, but this does not take into account your tank’s dimensions, filtration, or inhabitants. For most systems, you will need at least 1 to 2 inches of substrate. If you have a high flow rate in one area of your tank, your substrate may be slanted and require a gradient between a bare bottom up to 2 inches. If you have digging or bottom-feeding fishes or invertebrates, you may need a slightly deeper substrate to accommodate their building and foraging behaviors.
If your substrate is too deep, you run the risk of bacteria losing contact with oxygen in the water. This forms pockets of anaerobic bacteria, which use sulfur as a food source. If they are ever disturbed, they can potentially release deadly hydrogen sulfide into your tank, which can harm your fish and invertebrates. Some advance filter systems harness the filtration capacity of these unique bacteria, but they require constant water flow to be effective in a marine environment, not buried in your substrate.
What is the best color of sand for a reef tank?
Sand color preference is entirely at the discretion of the hobbyist. There are very few fish in marine tanks who live in deeper depths and prefer a darker substrate, but they are not common in the hobby. Lighter substrates will show algae more than natural colors, so you may need to clean them more frequently or decrease your algae load. Your intended tank’s aesthetic is entirely your choosing.
Do I need a sand stirrer for my reef tank?
If your sand is deeper than an inch or two, you will need to periodically stir the sand at the bottom of your tank in order to keep it aerated. A sand stirrer does not have to be anything fancy; just a clean plastic stick will do the job. Do not use plastic or metal to stir your substrate and only use it in your aquarium.
Do live sands need to be cleaned before I add them to my tank?
Full “cleaning” of substrates is not recommended. However, a rinse in treated saltwater prior to adding to your system will get rid of any dead bacteria and small particulates. You can easily do this in a bucket of waste tank water following a water change.
Can you use live sand in freshwater tanks?
Since these products contain live saltwater cultures, adding them to freshwater would instantly kill the bacterial colonies, producing an ammonia spike. It is not recommended to use live sand intended for saltwater systems for freshwater. There are freshwater products available if you desire to use them in your freshwater system.
Why Trust The Spruce Pets?
Dr. Jessie Sanders has eight years experience working full time as an exclusively aquatic veterinarian and spent years working in major public aquariums. She has extensive experience with a wide variety of aquarium products and how they directly impact the health of the environment and inhabitants.
A previous version of this article was written by Ashley Knierim.