How to Remove Algae From Fish Tank Decorations? – 3 Ways

how to remove algae from fish tank decorations

Understandably, many beginner aquarists want to learn how to remove algae from fish tank decorations. Although these greenish-to-brownish life forms can make an underwater castle look more vintage, algae can detract from the fish’s vibrant colors and the aquarium’s beauty.

To get rid of algae in aquarium decoration, follow the three steps and methods we share here.

Ways to Remove Algae from Fish Tank Decorations


What to prepare

This activity does not require too many materials. You can clean algae from fish tank with only the following items.

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  • Hot water, vinegar, or bleach (depending on your preferred method)
  • Aquarium sponge, scrub, or toothbrush
  • Bucket, basin, or container for the fish tank decorations


Step 1: Remove the aquarium decorations.

Carefully dip your hand into the fish tank to remove each decoration (including rocks and fake plants) covered with algae. You do not want to agitate the water too much to avoid stressing your fish.

Place the aquarium decorations in a bucket or container, making it easier to get algae off fish tank decorations.

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Please do not clean algae off aquarium decorations without removing them from the fish tank. Although vinegar is safe, it is acidic and could stress your fish by altering the water’s ideal pH.

Other methods (i.e. hot water and bleach) also require caution. This activity also calls for scrubbing the algae off decorations’ surfaces, which can further stress the fish.


Step 2: Choose your algae removal method.

Ridding your aquarium decorations of algae depends on the type of décor you have. For example, although bleach is effective, it is corrosive and can cause discolorations if your decor is bright in color. It is also inadvisable for wood; use bleach for plastic and gravel only.

Method 1: Soak the fish tank decorations in recently boiled water for at least 15 minutes.


Soaking in hot water is the most natural way to remove algae from fish tank decor.

Boil enough water to cover all fish tank decorations in the bucket to ensure everything stays submerged. This action is crucial because you do not want algae to remain on the aquarium decorations.

However, we do not recommend hot water immersion to clean algae from aquarium descor made of plastic because they tend to melt.

Fifteen minutes of hot water immersion should be enough to dislodge algae from decoration surfaces. You can extend it to 20 minutes, although the water might no longer be as hot.

Place each décor under running tap water to rid the algae.

You can brush the fish tank decorations lightly with a scrub pad or toothbrush if you have algae that will not come off with ordinary rinsing. Ensure to scrub crevices or spaces to remove all algae.

Method 2: Clean the aquarium decorations with bleach solution


This method is perfect if you are concerned about hot water melting some fish tank decorations. Bleach can be an excellent method to clean plastic aquarium decorations.

Ensure the bleach only contains sodium hypochlorite and nothing else.

Prepare a bleach solution comprising 95% warm water (not scalding hot) and 5% bleach. For example, mix 0.25 gallons of bleach with 4.75 gallons of warm water to make a 5-gallon bleach solution.

Please wear a face mask and rubber gloves to protect against bleach-related skin and airway irritation. You might have the best way to remove algae from your aquarium decorations, but everything will be for naught if you harm yourself.

Pour the bleach solution into a bucket or basin and soak the fish tank decorations for ten minutes.

Assess the algae and see if they are starting to peel off from the fish tank decorations. If not, extend the bleach solution immersion up to an hour (but never beyond).

Brush the surfaces to remove as much algae as possible.

Method 3: Immerse the fish tank decorations in vinegar for at least five minutes.


Eliminating algae from fish tank decorations with vinegar is effective and practical. Vinegar is also a safer alternative to bleach and can be a viable solution for households without bleach products.

For this method, fill a bucket or basin with 0.5 gallons of warm distilled or pure water and add about 120 milliliters or four ounces of vinegar.

Immerse the fish tank decorations in the vinegar solution, then get a toothbrush or algae brush and scrub the decorations’ surfaces, including tiny spaces or cracks.

Step 3: Rinse the fish tank decorations very well before returning them to the aquarium.

Rinsing the fish tank decorations vary across methods. For instance, the hot water technique requires rinsing aquarium decors with tap water, while the vinegar solution trick demands washing off with warm water.

Meanwhile, the bleach method requires soaking the fish tank decorations in warm water overnight. This extra step is necessary to remove the bleach entirely.

After overnight warm water immersion, you can rinse the fish tank decorations a second time. Moreover, you must prepare a dechlorination tablet and follow the instructions for making dechlorinated water.

Return the decorations into the aquarium as carefully as possible to avoid stressing the fish.

Tips to Prevent Algae From Growing Back


Cleaning green algae on rocks in aquarium units and other fish tank decorations is easy. However, aquarists must also observe some measures to prevent these organisms from growing back or at least retard their growth.

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  • Turn off fish tank lights at least 16 hours daily to deprive algae of an energy source.
  • Change 15 to 30 percent fish tank water weekly to prevent algae spores from growing.
  • Replace fluorescent lights every six months to avoid causing light wave changes that foster algae growth.
  • Wash the fish tank regularly to remove food, which will help clean brown algae, green algae, and other organic matter that can fuel their growth.
  • Scoop dead organisms (i.e., fish, other livestock, and plants) from the fish tank to deprive algae of food sources.
  • Assess the fish tank filtration system and protein skimmer weekly to ensure they remove waste.
  • Test the aquarium water weekly to check nitrite and ammonia levels. Although this action does not prevent algae from growing back, it gives you an idea of any potential problem. You can address the issue to curb algae growth.



How to remove algae from fish tank decorations is a straightforward activity you can finish in an hour, depending on the preferred method.

The vinegar technique offers the most convenient and practical way for removing algae growth from fish tank decorations. It is not messy, and you can finish the job within half an hour.

Hot water immersion is also convenient and effective. Unfortunately, this method is not advisable for plastic aquarium plants because of the risk of melting.

The bleach technique is excellent, although time-consuming and tedious.

So, which is your favorite?