How To Clean Aquarium Rocks Of Algae (Step by Step)

Algae is a type of bacteria found in many places such as ponds, lakes, and oceans, but it can also grow in your fish tank. Although virtually every fish tank has some type of algae growing in it, too much of the bacteria can cause problems to your fish and aquarium plants if it gets out of control.

The most efficient way to clean aquarium rocks of algae is by using a vinegar solution. This method helps to get rid of both algae and calcium buildup, as algae often draw calcium and other minerals from seawater for food.  You can also use hot water and bleach to remove debris and algae from your decorative rocks.

The exact method you will need will often depend on the extent of algae growth and whether you have sensitive aquarium plants in your fish tank. In this article, we are going to explore the various methods of removing algae from aquarium rocks.

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  • Contains one (1) API ALGAEFIX Algae Control 16-Ounce Bottle
  • Controls algae growth and keeps aquarium glass, ornaments and plants clean
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  • Will not harm fish and plants when used as directed
  • Dose every three days until algae is under control then dose weekly

Last update on 2022-06-28 / Affiliate links / Images from Amazon Product Advertising API

How To Clean Aquarium Rocks Of Algae Using Bleach

Algae in your aquarium can come in many forms: red, blue, green, black, or white. It can also appear puffy, mossy, or stringy. Whatever it looks like, you need to get rid of algae in your fish tank as soon as you see it. Even if it looks little today, it has the potential to colonize your entire tank given the right conditions. Here are a few steps on how to use bleach to clean your aquarium rocks and other tank decorations of algae.

  1. Remove the aquarium rocks from your fish tank. Be sure to remove the decorations gently and one at a time to avoid stressing out your fish. You should also be careful not to knock off and release any algae directly into the water.
  2. Expose the substrate by moving all live plants to one corner of the fish tank. Clean off any debris on the rocky substrate using a gravel vacuum and aquarium siphon.
  3. Place the aquarium rocks and other decorations in a pot of boiling water and leave them there for about twenty minutes. The hot water should be enough to kill off most of the algae.
  4. Scrub the decorations thoroughly with a toothbrush, being sure to reach all the nooks and corners to get rid of as much algae as possible.
  5. In a bucket, prepare a bleach solution with 5 percent bleach and 95 percent warm water. Put on a pair of gloves to avoid burning your hands, and then soak the aquarium rocks in the bleach solution for about five minutes. Scrub the decorations once more using your toothbrush.
  6. Rinse off the decorations thoroughly with cool water then again with warm water. You want to ensure there is no bleach remaining on the rocks when you put them back in the fish tank, as it can present serious health problems for your fish and plants.

If there is an issue with chlorine in your water, you can easily neutralize it with a dechlorinator. Simply add dechlorinator in a bucket of water and soak the rocks for a few minutes before you put them back in the fish tank.

Related article: How to clean plastic plants in aquarium

How To Remove Algae From Aquarium Rocks Using Vinegar

Removing algae from smooth aquarium rocks is relatively easy, but you need a different solution when working with rocks that have rough surfaces. This is where vinegar comes into play. Vinegar helps to eliminate mineral deposits that are typically left behind when hard water evaporates, and it can also double as an effective disinfectant for your fish tank.

Method 1

In a plastic bucket, prepare a vinegar solution using water and white distilled vinegar in a 1:1 ratio.

Soak your aquarium rocks in the vinegar solution for at least 24 hours. The algae should be dead after one day.

Next, wash the rocks properly to get rid of mineral residuals and then set them aside to dry.

Note: Do not dip your rocks in vinegar if they are made of calcium carbonate. Vinegar is an acid and hence will dissolve bits of the calcium carbonate in the rocks to release carbon dioxide.

Method 2

Get a new toothbrush

Dip your toothbrush in a vinegar solution then scrub the surfaces on your aquarium rocks with algae buildup.

Related article: How to prepare lava rocks before putting them in the fish tank

How To Remove Green Algae From Aquarium Rocks With Hydrogen Peroxide

If your aquarium rocks have been infested with stubborn green algae, you should be able to get rid of it with hydrogen peroxide.

  1. Combine freshwater with hydrogen peroxide in a bucket.
  2. Soak your aquarium rocks in the hydrogen peroxide solution and leave them for a few hours.
  3. Rinse the rocks properly and set them aside to dry.

Hydrogen peroxide has numerous aquarium applications when used properly, but you should always consider it as a last resort and only after the other methods have failed. This is especially true if your fish tank contains certain plants such as Riccia fluitans (liverwort) or Riccardia sp. (coral moss), which are highly sensitive to hydrogen peroxide.

The recommended dosages of the 3% hydrogen peroxide solution for the different green algae species are:

  • Blue-green algae – 8-15ml per 50 liters of water
  • Green algae – 25-35ml per 50 liters of water

More algae in your fish tank means more nutrients being sucked out of the water. The result is that your aquarium plants will not get enough nutrients, which they usually absorb through the substrate and water column.

Having excessive algae in your aquarium also makes the water to appear cloudy and virtually everything to look dirty, which is not an attractive look. What’s more, a big algae bloom comes with increased demand for resources, which may be too overwhelming for your filter to handle.

Once you know how to clean aquarium rocks of algae, you can be able to regulate the growth of algae on your aquarium rocks and other decorations. Some level of algae is not all that bad for your fish tank, especially if you are looking to create a serene environment for certain types of fish such as betta. Just be sure to keep the algae under control and make a point of cleaning your aquarium every now and then.


About Me

My name is Jason Matthews and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

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