1. What kind of sand is safe for use in a reef tank?

Most sand for saltwater aquariums and reef tanks is made of aragonite.  Aragonite is a calcium carbonate-based mineral, the same stuff that makes up coral skeletons and the same stuff that makes up natural sand found on the seafloor. It is safe, has been used very successfully in aquariums for decades, and there is a variety of different types that are generally differentiated by grain size and appearance.  

There are other options out there and the most common alternative is the Hawaiian Black Sand which aesthetically has a very unique appearance in the tank. The downside is the sand grains are sharp and not as accommodating for sand-dwelling/sifting animals and it typically contains magnetic particles that can get stuck on algae magnets and pump impellers.  

2. What is the BEST substrate for a reef tank?

So the answer here can be somewhat subjective but there is one particular sand that has proven to be the most popular for a few reasons. Caribsea Special Grade Reef Sand has a uniform appearance with a grain size that is easy to keep clean and won't be easily kicked up by pumps and strong currents in the display. It is also suitable for a variety of the sand-dwelling animals we keep inside reef aquariums. 

The second runner-up in terms of popularity is the Caribsea Fiji-Pink which contains a slightly smaller grain size and creates a more sandy appearance in the tank which some aquarists find more desirable. The downside is this fine grain size is easier to be stirred up by pumps and can be more difficult to siphon clean without removing sand in the process. 

3. Do all saltwater aquariums need to have sand?

The short answer is NO, live sand is not mandatory but is highly recommended for most saltwater tanks. Keeping a bare-bottom tank (saltwater aquarium without substrate) is most beneficial in SPS dominant reef aquariums because you can increase water flow without worrying about stirring up the sand or constantly moving it around the tank. You can also easily remove collections of detritus and leftover food from the bottom of the tank without having to siphon through the sand. While these benefits are great, a bare-bottom tank really should be reserved for expert-level aquarists because the benefits of keeping sand in the aquarium are far more beneficial for the vast majority of saltwater aquarium owners.

Benefits of live sand in a saltwater aquarium

  • Aesthetically pleasing and creates a natural composition
  • Provides critical habitat for fish and invertebrates
  • Supports beneficial bacteria and the resulting microbiome that is fundamental to the stability of your tank
  • Quickens cycle times and improves stability

4. How much substrate do I need?

We recommend no more than 1 - 2" of sand to cover the bottom panel of your aquarium. Anything more than 4" deep becomes difficult to keep clean and doesn't provide additional benefits. Use the sand bed calculator to find out exactly how much sand you will need to buy for your tank based on the dimensions. 

5. Should I use LIVE or DRY sand for my new aquarium?

Live sand is wet and comes with beneficial bacteria which helps to create a stable cycle in a new aquarium and is highly recommended if you're using dry rock. Dry sand will eventually become alive in your tank but this will take time and is only recommended if your going to use established live rock that already contains living beneficial bacteria.

The theme here is beneficial bacteria, you really want to start your aquarium with either sand or rock (or both) that contains some level of beneficial bacteria for stability sake and to improve the entire cycle process.