Can Crushed Coral Be Used in an Aquarium?

Choosing the right aquarium substrate is a critical decision to make, whether it’s freshwater, saltwater, planted, reef, or any other type of aquarium setup.

Aquariums with glass bottoms aren’t recommended because they don’t represent a natural ground setting for fish, which is particularly true when they reflect the light coming off the fixture from the top of the tank.

Aquarium substrates, such as crushed coral, are thus used to give a natural look and serve as colonizing and breeding grounds for bacteria that benefit your fish.

So to give you a quick answer to the question of whether crushed coral be used in an aquarium – yes, you can use crushed coral as a substrate in your aquarium. But, it may not always be a good idea to use it (as covered later in this article)

What Is Crushed Coral?

Crushed coral is a common aquarium substrate that is composed of coral skeleton pieces, shells, and limestone.

Substrates with large grain sizes are easily whipped by strong water flow, causing sandstorms and debris build-up in aquariums.

To prevent this problem, large-grain substrates are crushed into smaller grains that are suitable for aquariums with a strong flow of water.

Benefits of using Crushed Coral in Aquarium

As an aquarist, you must be aware of the importance of your aquarium’s pH level in maintaining a healthy environment for the fish to survive and thrive in.

Decaying organic matter, uneaten fish food, and other biological leftovers can decrease the tank’s pH level over time. This makes it extremely important to keep a proactive check on the tank’s pH level and determine whether any changes are required.

Coral skeletons that make up crushed coral consist of calcium carbonate, which helps increase your aquarium’s pH level up to 7.6 without the use of any chemicals.

If you wish to increase the pH level further, all you need to do is either add crushed coral to your filter or simply drop a handful of it on the tank base. Either way, you will have to wait for a few hours to notice any changes in the pH level because the effect of crushed coral on the aquarium’s pH is quite slow.

Since most tropical fish do not require a pH buffer, crushed coral is not needed for regular tropical aquariums. However, they are ideal for use in brackish, marine, and reef aquariums and are perfect for African Cichlids in freshwater.

Best for African Cichlids

The reason crushed coral is recommended for keeping African Cichlids is that it caters to the high pH requirement of the fish.

African Cichlids are kept in saltwater aquariums that demand high levels of pH and alkalinity.

Crushed coral provides just that. The calcium carbonate present in crushed coral dissolves into the water slowly, increasing the water’s hardness level and providing a buffer to the pH and alkalinity levels.

Hence, crushed coral is often preferred by saltwater hobbyists and those who keep African Cichlids.

Related article: How to Soften Water For Aquarium?

Some Problems with Crushed Coral as Aquarium Substrate

Large-sized grains of crushed coral create some problems.

Uneaten food, dirt, and excrement, commonly referred to as ‘detritus,’ often settles or gets trapped between the grains, requiring regular maintenance of the sand bed.

If you procrastinate on cleaning the detritus, it will breakdown and decay, releasing ammonia, phosphates, and nitrates. These compounds are the last things you’d want in your aquarium because they feed the tank-destroying algae.

Another dilemma associated with large grains is that it deprives you of some of the most interesting fish species categorized as sand-sifting animals.

Starfish, Nassuarius snails, and gobies are examples of such fish that bury themselves in the sand and use their mouths to sift it through, serving as your incredible clean-up-crew.

The large grains of crushed coral prevent them from performing this function. Hence, it is best to use small-grain crushed coral or look for another alternative.

Should You Use Crushed Coral Now?

Many years ago, crushed coral used to be the most sought-after aquarium substrate, particularly among saltwater hobbyists.

But they’re rarely used today. New product alternatives that come with a better selection of grain sizes to suit various types of aquarium have replaced crushed coral nowadays.

They ensure a more balanced pH for your aquarium as well as promise a reduced detritus-trapping hassle.

You can always use crushed coral for your aquarium if you can commit to regular maintenance, but why should you when you have more promising options available on the market?

Dry or live sand is preferred these days, and the most popular options among them include aragonite and calcite.

Things to Consider in an Aquarium Substrate

To get the right substrate for your aquarium, you need to identify the underlying purpose and consider your preferences.

Is a healthy habitat your priority or are you more concerned with the aesthetic appeal?

The Aesthetics

When it comes to the looks, substrate combined with plants, driftwood, rock, etc, produces a visually pleasing landscape and creates a calming effect in your aquarium. A well-designed aquarium is thought to have health benefits for those who often glance at it.

There is a myriad of themes to choose from. For instance, a theme with the more natural brown gravel and driftwood will match the room décor. Gravel also comes with an added advantage of bearing beneficial bacteria that break down the waste generated from fish.

There are colorful theme options too. If you’re looking for a substrate for an aquarium in your child’s room, a mermaid or castle theme can be considered. Some people prefer the substrate color that complements their fish.

Many people believe that the color of your aquarium substrate should mimic natural fish beds for the welfare of the fish. This is not necessarily true.

Even if you select a color based on your personal choices such as fire-engine red, bright pink, neon blue, or other striking ones, the fish will do fine as long as you keep track of the regular maintenance, maintain good water conditions, and offer nutritious fish food.

While it’s true that these are not the colors they’d see in natural habitats, they remain unaffected by the color for the most part. In the bottom-line, the substrate color doesn’t directly harm the aquarium inhabitants.

Bacteria Medium

The substrate acts as a medium for beneficial bacteria to breed, grow and colonize. While the substrate is not the only such medium, it is where most of the bacteria reside.

As mentioned earlier, these bacteria play a significant role in removing the detritus and maintaining a hygienic environment for your fish.

Besides serving as a platform for beneficial bacteria, many types of substrates support the roots of live plants and draw nutrients. Some substrates provide key nutrients for use with live plants.

On the other hand, there are substrates that will not support live plants. Whether you plan to have live plants in your aquarium or not will determine the type of substrate you want.

The Type of Fish You Want to Keep

The type of substrate you select will also be determined by the type of fish you wish to keep in your aquarium.

After all, they are used as their habitat. Certain substrate types such as the sand ones are ideal for fish that like to burrow. Some bottom-dwelling fish tend to sift the substrate to collect the food particles that have fallen there.

As opposed to glass bottoms, substrates can make fish feel safer as it doesn’t reflect lights or images of other fish in the aquarium. Certain fish species hide their eggs at the bottom of the substrate.

Without sufficient substrate, the eggs will be easily accessible, and thus more likely to be consumed by adult fish. If you opt for a mottled substrate or one that’s large, eggs will be hidden or fall in between the open spaces, getting out of reach of other fish.

Substrate Materials

Besides crushed coral and sand, another commonly used substrate is gravel that comes in various sizes, shapes, and colors.

Large river rock is sometimes used with gravel or by itself that helps portray an attractive natural setting. For keeping egg-scattering fish species, marbles are used even though it’s far from natural.

They allow eggs to fall between them to protect them from adult fish. Marbles also allow for allowing for easy aquarium maintenance and are thus used in Betta Fish Bowls.

Final Word

Substrates are critical elements used in fish aquariums that not only contribute to the aesthetic appeal of your aquarium, but they also serve various functions pertaining to fish health.

Besides offering numerous colors and themes, they are important to maintain the precise hygiene levels for your fish. In fact, many fish species thrive due to certain types of substrates. Some types of substrates, however, can be harmful to fish.

Therefore, choosing the right substrate is an extremely important decision. Besides sand and gravel, crushed coral is a well-known aquarium substrate. Its primary function is to provide a buffer to your aquarium’s pH level.

However, with more sophisticated substrates available today, crushed coral has become outdated. This type of coral is still available on the market today, but other sand options such as calcite and aragonite now dominate the market and are preferred by most aquarists.

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