Live Sand for Saltwater Aquariums – Aragonite, Crushed Coral, Black Sand

Live sand for saltwater aquariums is like live rock. It contains beneficial bacteria that breaks down organics in your reef tank. Live rock is a more effective and doing this job and sand has started to become more just for looks than anything else. Some reefers prefer to not even have sand and go with a bare bottom tank. I personally prefer the look of sand versus a bare bottom tank but I’ve given it a long hard thought. I may go with one in the future but I haven’t done so yet.

Popular Live Sand Brands and Grain Sizes

Remember, the finer the grain size the more likely it will get blown around your tank. Finer grain sands tend to look better and are great for sand sifting fish but you’ll need to either adjust flow or deepen your sand bed if you want to avoid bare spots.

CaribSea - Fine Grain Size Live Sand

Bahamas Oolite

0.25mm – 1mm

CaribSea Oolite

Fiji Pink

0.5mm – 1.5mm

CaribSea Fiji Pink

Special Grade Reef

1mm – 2mm

CaribSea Special Grade Reef

Nature's Ocean - Fine Grain Size Live Sand

White Sand #0

0.1mm – 0.5mm

Black Beach

0.5mm – 1.5mm

White Sand #1

0.5mm – 1.7mm

Nature's Ocean - White Sand #1

Samoa Pink

0.5mm – 1.7mm

Nature's Ocean - Samoa Pink

Australian Gold

0.5mm – 1.7mm

CaribSea - Large Grain Size Live Sand

Hawaiian Black

0.25mm – 3.5mm

CaribSea - Hawaiian Black

Bimini Pink

0.25mm – 5mm

Indo Pacific Black

0.5mm – 5mm

West Caribbean Reef

1mm – 5mm

CaribSea - West Caribbean Reef

Natural Reef

3mm – 5.5mm

Nature's Ocean - Large Grain Size Live Sand

Reef Substrates

1mm – 2.5mm

Deep Sand Beds

In the not too distant past it was very common for reefers to have deep sand beds in their aquariums. The logic behind this was to create a low oxygen zone for bacteria to live forcing the bacteria to strip Nitrate of it’s Oxygen molecule and releasing the byproduct as nitrogen gas. Unfortunately any sand in your reef tank will eventually accumulate detritus that will need to be cleaned out before it begins generating the unwanted byproducts of the decomposition process. While many do still utilize deep sand beds, there really are better ways to control nitrate and phosphate. Live rock is the primary replacement. Reactors, refugiums, algae scrubbers, protein skimmers, and bio media are all additional methods of dealing with left over fish food and fish waste.

Bare Bottom Tanks

Bare bottom tanks are becoming popular since they make maintaining your aquarium much easier. There’s no way around having to clean a sand bed on occasion. Without the sand bed fish waste and excess food break down into the water column prior to decomposition and are largely removed by a protein skimmer. I’m all for simplifying tank maintenance but I’m personally not sure I can go all in on a bare bottom just yet.

If “live” sand isn’t really necessary, why should we use live sand for saltwater aquariums? Why not just use dry sand?

One of the great things about live sand is that it’s great for jump starting your aquarium if you’re starting with dead rock. We’re not going to dive into cycling a new tank in this article but live sand contains the same beneficial bacteria that live rock does. You’re not going to get hitchhikers from live sand and the bacteria can migrate to your rock quickly. There isn’t much cost difference between dry and live sand so there isn’t a reason to not use it if you’re going to use some kind of sand in your aquarium

Be sure not to discard the liquid that came with your live sand and keep an eye out for additional packets of clarifiers you can add to your tank that are often included.

What are the things to consider when buying live sand for your reef tank?

  • The most important is grain size. Grain size less than 1.0mm is great for your sand sifting fish. If you have a higher flow tank you’ll likely want to have a larger grain size so that it doesn’t blow around as much. Especially if you don’t intend to have thicker layer of sand. The thinner your sand bed, the more likely flow will create bare spots. The larger grains will stay put but but your sand sifting fish won’t be happy. You use a mixed formulation or buy a bag of each and put larger grain in first then top it with fine grain. This will prevent bare spots in high flow areas but still have plenty of fine grain sand for sand sifters.
  • Color is the next feature to consider. This is really all down to personal preference. In general you’ll find variations on traditional looking sand and black. Black Hawaiian sand can look stunning but it’s limited to a somewhat larger grain so keep that in mind.
  • The more natural types of live sand will tank a while to settle in a new tank. While not something that would prevent me from buying any particular type of sand it’s worth bearing in mind and planning to be patient for a few days.
  • How much sand to buy is also a big question to consider. Usually 1/2″ to 2″ is the typical range of thin to thick. 1″ is a pretty good compromise. Thin sand beds tend to be easier to maintain while thick ones will not end up with bare spots but will likely require regular siphoning out of debris. We’ve included a sand bed calculator at the bottom of this post to help you figure out how much sand you’ll need once you decide how thick you want to go.
  • Planning how to keep your sand bed clean is the last key factor. A clean up crew geared toward this job is a good choice. Starfish, sand sifting fish, crabs, and some snails may be enough for thinner sand beds. Thicker sand beds will almost certainly require siphoning.

Aragonite, Crushed Coral, and Black Sand

Aragonite and crushed coral are generally pretty similar except aragonite is typically a fine to medium sand and crushed coral is pretty large. Both contain calcium carbonate which can be good for coral growth. Black sand typically doesn’t contain calcium carbonate. Many corals need calcium to grow and it’s possible that calcium from your sand bed can be a source but if that’s true it certainly shouldn’t be the main source of calcium. Dosing kalkwasser or using a calcium reactor is way more effective. Choose your sand for it’s aesthetics and not for it’s calcium content.

Sand Bed Depth Calculator

The general rule of thumb is 10 pounds of sand covers 1 square foot at a depth of 1 inch.

Final Comments and Suggestions

Personally I love the super fine sand but I use the CaribSea Fiji Pink which is pretty popular which is slightly less fine than the gorgeous CaribSea Oolite. I have a slightly taller tank with a fairly dense amount of rock so I haven’t had any issues. Hopefully this info has been informative and helped steer you down the right path. Good luck and happy reefing!

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