What’s in your aquarium?

Keeping an aquarium is a fun hobby, whether you have a small goldfish tank or an elaborate marine tank. It can be as simple or as difficult as you make it. When you’re setting up your aquarium, one of your first and most important purchases is the substrate. Substrate is the layer of sand or gravel that you place at the bottom of your tank. Choosing the right substrate directly impacts the health of your tank. For example, in a freshwater tank, you would want to use a gravel or rock that won’t affect the pH of the tank. However, in a marine tank, there are options that will help you maintain a stable pH, without the addition of chemicals. The best substrate for this is oolitic aragonite. Coral sand can also be used, but it’s buffering capabilities aren’t as effective and it is usually unsustainably collected, and its collection can damage the reefs. 

Oolitic aragonite is a unique type of biogenic calcium carbonate. It naturally forms on the banks of The Bahamas on a sustainable and renewable basis. Due to its renewable nature, it is an environmentally responsible alternative. It has no harmful tar, impurities, or organics and is the ideal substrate for marine, reef, and cichlid aquariums. Oolitic aragonite has unsurpassed buffering capabilities and helps to maintain a natural pH balance of 8.2 without the constant addition of chemicals. One kg of aragonite also offers over 1 million sq. cm. of surface area providing a huge space for housing ammonia, nitrate, and nitrite reducing bacteria. It’s also the ideal grain size for reef tanks, fish tanks, plenum systems, and refugiums. Another benefit is its lack of silica, which helps to prevent diatom blooms in your tank. You’ll be hard pressed to find a better substrate for your marine, reef or cichlid tank. 

Unfortunately, however, there are many substrates out there that are all a bit of smoke and mirrors. They masquerade as oolitic aragonite, but under close inspection, they are either coral sand or just regular calcite sand. In order to reap all of oolitic aragonite’s benefits, you need real oolitic aragonite. Otherwise, you’re paying a premium for a substandard product that won’t perform the same as real oolitic aragonite. Fortunately, it’s quite easy to tell if what you are purchasing is indeed real oolitic aragonite. 

The easiest and quickest way to figure out if the product is indeed real aragonite is to look at the individual grains closely. Grains of oolitic aragonite are smooth and spherical. The word “oolitic” literally means egg-shaped. If the grains you are observing are rough and angular, this is likely just crushed shell or regular sand. It’s important to note that some aragonite substrates are a mix of oolitic aragonite and crushed shell. If you see a combination of spheres and angular crushed shell, this is likely a mix. It will provide the same benefits as purely oolitic aragonite since it still contains oolitic aragonite. The difference between them is simply aesthetic. 

FIGURE 1. QUICK AND EASY WAY TO DETERMINE IF YOU HAVE OOLITIC ARAGONITE.

Once we found out that there were some substrates masquerading as oolitic aragonite, we decided to take our analyses further. We went to the local pet store and bought a substrate that was labeled to contain “Bahamas Oolite Aragonite” to compare it to our oolitic aragonite that is sustainably harvested from The Bahamas. We had some remarkable findings!

Take a look at the below image of our oolitic aragonite compared to the other store-bought product labeled as oolitic aragonite. Do you see the round spheres in the image on the left? Those are oolitic aragonite grains – called “ooids.” Notice how the product on the right doesn’t have any round spheres and the grains are angular – that is simply regular sand and will provide none of the benefits discussed above. Unfortunately, the sand on the right is being sold as oolitic aragonite!

FIGURE 2. COMPARISON OF CALCEAN’S OOLITIC ARAGONITE TO A COMMON STORE-BOUGHT BRAND LABELED AS “BAHAMAS OOLITE.” CALCEAN (LEFT). STORE-BOUGHT BRAND (RIGHT).

After our initial visual inspection showed that there were no ooids, we examined the material under our lab’s microscope. You’ll notice the difference between our oolitic aragonite and the other store-bought product. Calcean’s oolitic aragonite has distinct spherical grains (ooids) whereas the other store-bought brand has angular grains indicating that it is not oolitic aragonite.

FIGURE 3. COMPARISON OF CALCEAN’S OOLITIC ARAGONITE TO A COMMON STORE-BOUGHT BRAND LABELED AS “BAHAMAS OOLITE.” CALCEAN (LEFT). STORE-BOUGHT BRAND (RIGHT). NOTE THE SPHERICAL GRAINS ON THE LEFT COMPARED TO THE ANGULAR GRAINS ON THE RIGHT.

We then took it a step further, conducting what is called the Feigl’s Solution test. This is a classic test used to determine whether a material is aragonite or calcite. When aragonite is exposed to the Feigl’s chemical solution, it will react and turn black immediately. It’s a quick and easy way to tell if what you have is aragonite. As you can see below, the store-bought “Bahamas Oolite Aragonite” is still white and our material turned black immediately. 

FIGURE 4. RESULTS OF THE FEIGL’S SOLUTION TEST. THIS TEST DETERMINES ARAGONITE FROM CALCITE. ARAGONITE IMMEDIATELY TURNS BLACK WHEN EXPOSED TO THE SOLUTION. CALCITE REMAINS WHITE. NOTE THAT CALCEAN’S OOLITIC ARAGONITE TURNED BLACK IMMEDIATELY INDICATING IT IS INDEED ARAGONITE WHEREAS THE STORE-BOUGHT BRAND REMAINED WHITE INDICATING IT IS NOT ARAGONITE.

Another issue to look for is material that is sold wet. The packaging will make claims of live bacteria, but there are no more bacteria on wet material than there are on dry material. This means you’re spending money on water rather than actual substrate. We actually dried and measured the amount of water in a 20lb and 10lb bag of store-bought wet or “alive” substrate. There was 4lbs of water in the 20lb bag and 2lbs of water in the 10lb bag! When you buy dry material, you’re getting what you pay for: substrate. There’s no need to pay for water!

 We were dismayed to see that companies are fooling the public into buying a falsely-labeled material, foolitic fauxragonite if you will. At Calcean, we strive to provide the best and most consistent quality products. Oolitic aragonite has a number of benefits and is an excellent aquarium substrate, when what you have actually is oolitic aragonite! You don’t want to waste your money on fake aragonite and water. Be a diligent consumer and examine your substrates closely and confirm the source. We’re proud to say that we provide sustainably harvested REAL oolitic aragonite. 

CALCEAN & PISCES USA’S REAL OOLITIC ARAGONITE PRODUCTS. SOLD ON AMAZON & CHEWY.