The Ultimate Guide on Live Rock Curing for Saltwater Aquariums or Reef Tanks

Aquariums are an exciting addition to a living or working space. They bring a feeling of life in the deep sea.

Compared to the past, things have changed from the simple aquariums to the more exciting reef tanks. Reef tanks provide a whole new experience by allowing you to observe corals and other invertebrates grow in the saltwater aquarium. They give you a view of the marine life in another dimension.

Although there’s a wide range of designs, there is one universal about all reef tanks: live rocks. Reef tanks must have live rock, and the rocks must undergo a curing process to suit the climate of the saltwater aquarium.

Luckily, the curing process is something you can accomplish at home. Here is a guide on how to cure live rocks like a pro.

What Is Live Rock?

Live rock consists of rubble that has broken from a coral reef due to natural conditions such as tropical storms or hurricanes. The reason why this rubble is “live” is because it contains living organisms. The reef houses millions of species, including crabs, small crustaceans, sponges, bacteria, and algae, among other organisms.

Live rock in marine aquariums serves the following purposes:

  • It provides living and hiding spaces for saltwater fish. The rock gives your invertebrates and fishes a natural area where they can experience an ecosystem similar to the ocean.
  • It offers essential biological filtration. Biological filtration is a process that allows the development of beneficial bacteria, which is critical for filtering the saltwater aquarium water. The filtration breaks down wastes into nitrogen compounds.
  • It makes the aquarium more colorful. Attractive pink and purple coralline algae form on the rock after some time, creating a vibrant array of colors and species.
  • It furnishes nourishment for invertebrates and fish. The rock can be a source of food for organisms in the reef tank.
  • It makes the saltwater aquarium look more natural. Live rock mimics the natural environment of the deep sea.
  • It enables new organisms to spring to life once the rock has cured. These organisms can be fascinating to watch.

To enjoy the many benefits of live rock in your saltwater aquarium setup, you need to cure it first. Before we delve into the process of how to cure live rocks, it’s crucial to understand the difference between pre-cured and uncured live rocks.

Pre-Cured Live Rock

Curing live rock is a process that involves removing all decaying or dead matter within and on the surface of the rock. Pre-cured or cured rock is one that has remained in a separate tank that doesn’t have fish for a few weeks before sale.

The pre-curing process eliminates all the dead or dying organisms from the rock’s surface. This process must occur before placing the rock in a high-circulation curing tank. In some cases, a mist of saltwater continuously sprayed over the rock can enhance the removal of dead organisms.

Retailers usually do most of the pre-curing work. However, you might need to do some extra curing to be 100% sure the rock is ready for use.

It’s essential to allow a quarantine period to ensure the identification and removal of any parasite that might be hiding in the rock. The risk of parasites and infestations are why it’s crucial to cure the rock before transferring to your saltwater aquarium.

Uncured Rock

Uncured rocks cost less, usually a third of what it would cost to buy a cured one. While these rocks are cheaper, you have to do the curing yourself, which might require specialized tools and additional expenses.

To deal with uncured rock, you need to set up a new tank for the curing process. You also can use the more affordable trash cans or plastic containers. Remove all the debris from the rock before placing it in your curing container. You can use simple tools, like an old toothbrush, to scrub off any dead organism from the surface of the rock.

Later in the guide, we give a detailed step-by-step for two methods of curing live rock.

The process for uncured rock requires regular monitoring of water parameters to check nitrate, nitrite, and ammonia levels. Change the water frequently until there are no nitrogen compounds detectable in the water.

Once you can be sure there is no presence of foul smell or nitrogen compounds, you can conclude that your rock has cured completely. How long the curing process takes may differ based on the shape of the rocks.

Why Curing Live Rock Matters

The curing process is essential for removing all the toxic compounds present in the rock. This vital step ensures the fish get a clean and healthy marine environment that is free of ammonia and other compounds.

Pre-cured live rocks undergo die-off, a natural process that typically occurs with delicate or damaged flora and fauna. The die-off produces toxins and compounds that can affect the health of your fish or invertebrates, which is why curing is necessary for most types of live rock.

Is the Curing Process Necessary for All Live Rocks?

No. Curing is only necessary when there are signs of decomposing or dead matter in the rocks. There are two ways to check this:

  • Smelling the rock. Hold your nose up close to the rock and smell it. If you notice a strong odor like that of rotten fish, then you need to cure your rocks. If the smell is like that of the ocean, then it’s ready for use.
  • Test for ammonia. Place your live rocks in a tank containing saltwater and wait for 12-24 hours. Test the level of ammonia after the 12 or 24-hour duration. If the level of ammonia is zero or very minimal, then your rock is ready for use. If the ammonia content is high, you need to carry out the curing process. Testing for ammonia is a more scientific and accurate method compared to smell.

There are certain rocks for which curing is mandatory, for instance, the Indo-Pacific and Live Rock from Fiji. These rocks undergo transportation over long distances, which will likely lead to die-off.

Temperature differences between the source of the live rock and your location also will determine whether curing is necessary.

What Are the Differences Between Dry and Live Rock?

Live rocks contain microscopic marine life existing in and on the surface of the rock. These organisms are visually appealing when used in aquariums. They also provide biological nitrification and natural water stabilization, which gives your fish a healthier environment.

However, it’s not easy to know the kind of organisms or pets may be lying inside your new live rock. There might be potential hitchhikers, such as crabs and mantis, which you will only notice after purchasing the rocks.

Dry rock is simply wet live rock that has gone through a drying and cleaning process before it goes into the aquarium. Although dry rocks also contain living organisms, it can take longer for the algae to develop. Furthermore, the algae growing on dry rocks might not be as suitable for an aquarium compared to that of a live one.

Due to the high demand and scarcity of live rocks, they tend to be more expensive. Dry rocks weigh less and are cheaper. You need to learn how to cure dry live rock before placing it in an aquarium.

How to Cure Live Rock: 2 Methods Step-by-Step

The process of how to cure live rock is not complicated, but it does require thoroughness and precision. With the right tools and guidance, you can cure your rocks in a few weeks. Here are the items you will need to make this procedure successful:

  • Saltwater test kit (for testing nitrite, nitrate, and ammonia levels)
  • Live rocks
  • A heater
  • Empty tank, bucket, or container
  • An air pump

Method A (Curing Live Rock When Fish Are Not Present)

Follow these steps to understand how to cure live rock for saltwater tanks.

Step 1

Fill your empty tank or container with saltwater. It’s preferable to have a glass tank because it makes it easier to observe the rocks and get rid of all unwanted things.

Step 2

Warm the water to around 80°F and place your rocks inside the tank. Put the airline of your air pump in a way that allows sufficient and consistent water flow through the rock. If you have a wavemaker, you can use it to make the process more efficient.

Step 3

After a few days, check the level of ammonia using your saltwater test kit. You’ll likely notice an ammonia spike, followed by a nitrite spike and, finally, a nitrate spike.

Retake the readings after a few days. The nitrite and ammonia readings should be zero at this point, but there will still be traces of nitrate. These readings are an indication that biological filtration has taken place, and the rocks now have enough bacteria colony to take in nitrate and ammonia. The remaining nitrate should not worry you; it is safe for the saltwater to contain some level of nitrate.

Step 4

Test the water regularly until you notice consistent nitrate levels. This equilibrium indicates the dying of sponges and residual corals is complete and no longer releasing nutrients. Once you record consistent nitrate levels, you are ready to place the rocks in your aquarium.

Points to Note

  • If you notice any unwanted creature during the curing process, remove it immediately using a brush.
  • It takes between 4 to 6 weeks for the rocks to cure completely.
  • It’s essential to do a final check for any unwanted creatures or pests before placing your rocks in the main aquarium.

Method B (Aquarium with Fish)

When you already have a displayed aquarium, it’s essential to take extra care not to damage any corals, fish, or invertebrates during the curing process. Follow the steps below for curing live rock with fishes present:

Step 1

Remove your live rock carefully and place it in a new tank, preferably a container with a 30-gallon capacity. What you want here is to drain the water completely from your live rock. Adding bottom drains to the box will speed up the draining process.

Step 2

Fill your container with freshly mixed saltwater until you have covered the rock completely. Maintain a gravity of between 1.021 and 1.025.

Step 3

Heat the water and maintain the temperature at 80°F. This temperature will speed up the die-off.

Step 4

Use your air pump to provide consistent water movement through the rock. Ensure you conduct this process in a dimly lit place to avoid algae blooms.

Step 5

Change the water regularly, at least twice a week. Use your brush to scrub the rock between water changes. This extra measure helps to eliminate any dead material or white film that might have formed on the surface of the rock.

Once the ammonia and nitrite levels hit zero, your rock is ready to go back to the aquarium. This process will take between 1 to 3 weeks.

Factors to Consider During Curing

There are several things you need to observe during the curing process:


Exposing your live rocks to full intensity lighting may lead to an algae bloom. The best option is to light them with natural or actinic lighting. Some LED lighting kits use actinic lighting.

Place the rocks in a room without exposure to direct sunlight. If you opt for actinic lighting, do not exceed a photo-period of 5 hours per day.

The aim is to provide minimal light that will help to keep coral hitchhikers and coralline algae alive. If the amount of light goes beyond the required limit, then you are likely to notice algae blooms.

Foul Smell

The curing process typically produces a foul smell that may not be too comfortable for the residents. If you are planning to place the tank in a house, make sure it’s in a reasonable distance away from your living space. You can use carbon to dilute the smell.

Controlling Unwanted Pests

One of the unwanted creatures in live rocks is pests. To remove them altogether, submerge your rock in a bucket full of salt water for one minute. Make sure the gravity level is between 1.035 and 1.040.

This process will evacuate bristle worms, crabs, mantis shrimp, and all other invertebrates into the water. Once the process is complete, remove your rock and sort the type of invertebrates you want to keep or remove from your system.

Bottom Line

If you want to enjoy the beauty of a reef tank, it’s essential to understand the process of curing live rock. This crucial process will give your fish a healthy and favorable environment. No matter the type of rock you select, make sure it’s the best quality. Your selection will determine the level of curing you need and how your reef tank will look.

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Kelly Stanley