How to Clean Aquarium Rocks of Algae

Algae can form on rocks in almost any type of water, including in your aquarium. Although the life of this plant is beneficial in some ways, it can give off carbon dioxide as it decays.

Furthermore, algae have the potential to take over your entire tank if given the right conditions. So, if you want to maintain the oxygen balance in your aquarium, you may need to remove the algae in the rocks from time to time.

In this article, we’ve discussed how to clean aquarium rocks off algae to help you give your aquatic creatures a healthy and comfortable place to live in. 

Essential Steps on How to Clean Aquarium Rocks off Algae

how to Clean Aquarium Rocks off Algae

Cleaning aquarium rocks may seem like a difficult task at first, but once you understand the proper ways of doing it, you will find it easier and more convenient. Here are five basic steps to help you clean and maintain your aquarium rocks.

1. Remove the Fish in Your Tank

It’s highly recommended to remove all the aquatic creatures in your tank first, to make the cleaning easier. That way, you can clean your aquarium rocks without the fear of hurting your beautiful little pets.

Provide temporary shelter for the fish and ensure they have plenty of space. Non-chlorinated water is the best to use for their temporary shelter.

Read: Large bow front aquarium

2. Remove the Decorations from the Tank

Remove your aquarium decorations slowly and one at a time. Be careful not to shake the decorations to avoid knocking off any algae and releasing it directly into the water.

Also, detach your filter, remove live plants or tank equipment, and set them aside. Your tank should only be left with water and aquarium rocks, pebbles, or gravel.

3. Clean the Aquarium Rocks

Get a filter, remove all the rock from your fish tank, and place them in a strainer.

Some level of algae is easy to remove using a wet sponge or towel, but some make stubborn stains difficult to get rid of using little effort. Furthermore, some aquarium rocks have smooth surface while others are rough.

Removing algae from smooth rocks is easier than on rough or uneven surfaces.

Here’s how to clean the algae off your aquarium rocks using hot water and bleach solution:

  • Fill a bucket or pot with hot water.
  • Place the aquarium rocks inside the pot with hot water and let them soak for around 30 minutes. Make sure the water in the pot is hot enough to kill most of the algae.
  • Remove the rocks from the pot and rinse them with warm running water for at least one minute.
  • Scrub the rocks thoroughly with a stiff-bristle toothbrush, making sure you reach all the nooks and edges to remove as much algae as possible.   
  • Prepare a bleach solution with 5% bleach and 95% warm water in a bucket. Wear a pair of hand gloves to avoid burning your hands, and soak the aquarium rocks in the bleach solution for around 5 minutes. Scrub the rocks once again using a toothbrush.
  • Rinse the rocks with cold and then warm water to ensure that all the traces of bleach solution are washed away. Bleach traces can pose serious health issues to your fish and plants.
  • If you are concerned about chlorine in the water, get a bucket of water, add a de-chlorinator, and then soak the rocks in the dechlorinated water. After that, your rocks will be ready to be put back into the fish tank.   

See also: Is there a way to make a self-cleaning fish tank?

4. Put the Aquarium Rocks Back into the Tank

Once you have successfully cleaned your aquarium rocks, you can put them back again. Place them evenly all over the tank’s bottom. Reconnect your water filter and put your decorations according to your liking.

5. Set Up your Aquarium Back

After redecorating your tank, it’s time to put your fish back. If some of your fish need specific requirements, ensure you top up the remaining water with non-chlorinated water.

When everything is set, slowly submerge the container holding your fish to ease their way through and avoid unwanted injuries.  

FAQs on How to Clean Aquarium Rocks of Algae

Can Boiling Aquarium Rocks Kill algae?

Boiling your aquarium rocks will not kill the algae. High temperature doesn’t kill the algae, but it can worsen the situation. Boiling aquarium rocks can cause the algae to burst, releasing some harmful chemicals into the water.

How Can I Remove Brown Algae from Aquarium Rocks?

The most effective way to remove algae, including brown algae, from aquarium rocks is to scrub them down first with a bristle toothbrush to remove as much of it as possible. Next, you need to create a solution of about 10% bleach and 90% water.

Brown algae are extremely stubborn, so you need a more concentrated bleach solution. Once you make a bleach solution, soak the rocks in the mixture for about 30 minutes, and then scrub them down again with your toothbrush.

Remember to rinse your rocks off well with warm running water.   

Can I Use Bleach to Clean Aquarium Rocks?

You can use bleach to clean your aquarium rocks. Bleach solution is actually the most effective way of removing algae from aquarium rocks. Make sure you create a concentrated solution of not more than 90% water and 10% bleach.

Also, make sure to rinse off the rocks thoroughly after getting rid of the algae. Remember that any bleach residue in your aquarium can be dangerous to your fish and plants.

Cleaning aquarium rocks off algae is quite an easy task, but it requires time and effort. However, the best way to ensure you don’t have algae in your aquarium is to take care of the underlying cause right from the beginning.

Keep in mind that some level of algae is not that bad for your aquarium, especially when you want to create a peaceful environment for certain types of fish, such as betta.

Read: Best way to clean out tank after Betta dies


Pet Industry Association Australia [PIAA]: How to clean a fish tank

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