How to Get Rid of Algae in Fish Tank (Removal & Control)

how to remove aquarium algae
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Last Updated: August 25, 2023 by Flora Gibbins

Algae removal and control is just part of aquarium care – we are all going to see some in our tank at some point.

So, it will probably be re-assuring to hear that algae aren’t all that bad! They’re natural and (in essence) a plant so they can help oxygenate the tank.

However, in larger amounts algae can ruin the viewing experience of your tank and if not maintained it can get out of control causing algae blooms, taking over the whole tank and becoming hazardous to your aquarium.

By using a few simple steps which will continually control and remove any algal growth, you can keep your tank clean and healthy.

Oh, and just to point out that this algae prevention and removal guide is for all freshwater aquariums. Any betta fish owner specific tips have been called out.

How to Prevent and Remove Algae

Reduce Any Waste Fish Food

Phosphates and ammonia are two nutrients that increase algal growth in aquariums. The main contributors of these nutrients are unconsumed fish feed and fish waste.

In order to decrease these two nutrients in your water, you should try to feed your fish just enough food so that none is wasted.

For a large stocked freshwater aquarium only put enough food into the tank so that it is eaten within a few minutes. Any more is excessive and will lead to waste (and therefore algae). If there is any food left after a few minutes remove it with a net or pipette.

A good amount of food for betta fish is 2-3 pellets or a small pinch of flakes (in the morning and again in the evening). Check out our betta fish feeding guide if you need more information.

The amount of food and feeds can differ from fish to fish so be sure to look up recommended feeding schedules for your fish.

Less wasted food at the bottom of the tank, then less phosphate and ammonia in the tank which means less algae can grow.

Get Rid of Algae in Your Tank by Getting Rid of the light

Is your tank in direct sunlight? That is one way to have a algae problem! Always have your tank in an area of the room out of direct sunlight.

If you keep your aquarium lights on for extended periods of time then you are also increasing the rate of algae growth in your aquarium (just like a plant – light is algae’s source of energy).

Try to keep aquarium lights on for only 8 to 9 hours a day in tanks without many aquarium plants and 11 to 12 hours for aquariums with many live plants.

Timers can be helpful to keep aquarium lights on regular cycles and some lights, like this one, come with built-in timers. Also, certain types of LED light are designed to specifically help increase aquatic plant growth while reducing algal growth.

Turning off the lights is a great way of getting rid of algae in a tank that is already suffering badly. By ensuring little to no light reaches the tank you starve the algae of any energy/food. A great way of getting rid of algae fast!

Try turning off the light and covering the tank so not even daylight gets through for a few days.

Regular Water Changes

Clean water is THE staple of good aquarium care.

Regular water changes can help dilute and carry away unwanted algal nutrients that build up in your aquarium water.

Doing weekly water changes of 10-20% and a larger water change of ~30% every month will help keep your water clear. Some simple test strips, such as this one, should be able to test for chlorine, alkalinity, nitrite, hardness, nitrate, pH, and ammonia.

Keeping Your Tank Clean

Algal buildup on your aquarium’s acrylic or glass sides can make it hard to observe your fish, damage your aquatic organism’s health, starve plants of light and nutrients, and can harm water quality in high density.

An easy way to remove algae from your aquarium glass or acrylic is to use a scraper such as this one. The bottom substrate should also be siphoned regularly and can be easily done using siphons such as this one.

The aquarium Siphon

Even when algae isn’t yet visible, you should clean the glass and siphon the substrate as part of your weekly water change – this will keep algae at bay.

No algae can stand up against elbow grease and a scraper! Try and get into every nook and cranny.

Maintain Your Filter and Reduce Algae Growth

Maintaining your filtration media is another way to keep your aquarium’s algal content low.

In most cases, owners of aquariums will have a mechanical filter. When doing your weekly water change make sure to remove the filter media and wash it in aquarium water (at least every other week). You should replace the filter media if it begins to look clogged (water flowing through the filter slower than normal is a sign of this).

Most mechanical filters will also have a biological filter insert. There are several types of phosphate controlling medias on the market that can help increase the power of your biological filter.

Obviously always read the instructions on the box of the biological insert that you have bought, however, it’s common that you will usually need to change this every 4-6 weeks.

Maintaining your filter will help to decrease the chances of phosphates and ammonia building up in your system – and therefore reduce the amount of algae that can grow.

Reduce Algae Growth with Some Tank Mates!

We don’t mean just any tank mates, remember fish waste is an algae contributor, you want to get some algae eating tank mates.

Freshwater tanks can benefit from Otocinclus catfish, Black Mollies, Siamese Algae Eaters, Plecostomus, Amano shrimp, and snails. Always research the potential new pet to ensure it makes a good fit in your aquarium.

For a betta fish owner, good algae reducing tank mates include Otocinclus catfish, ghost shrimp, and snails. There’s many more. Before buying always make sure that they are a good betta fish tankmate.

You can also first research which type of algae you are dealing with so that you pick the best type of algae-eating herbivores to add to your aquarium.

Marine aquariums can benefit from Black Sailfin Blennies, Lettuce Sea Slugs, Hermit and Emerald Crabs, Court Jester Gobies, and snails (Cerith, Abalone, and Turbo).

As always is the case you should research which fish/organisms are compatible with the other fish/organisms already living in your aquarium.

Live Plants Can Reduce Algae

Since plants compete with algae for light and nutrients they help prevent the growth of algae. It’s always a good idea to keep several plant species in larger aquariums.

Plants that have been shown to do well in freshwater tanks include Red or Green Cryptocoryne, Round Leaf, Java Fern, Water Sprite, Anacharis, Hornwort, Dwarf Hairgrass, and Cabomba.

Good marine live plants to add to your aquarium include Red Gracilaria and Green Finger Algae, Mermaid’s Fan, Maiden’s Hair, Halimeda, Shaving Brush, Grape and Smooth Leaf Kelp, and Red Mangroves.

If live plants sound like the answer to you, we have a guide on how to add live plants to your tank and also the best live plants for beginners.

Water Movement and Aeration

Generally, this will not be an issue for betta fish owners as long as your tank has a mechanical filter through which water flows. This is because betta fish owner’s tanks are usually around 5 gallons, however, if you have a larger freshwater aquarium…

Stagnant water can lead to the buildup of organic material so actions should be put in place to keep the water flowing.

Aquarium circulation pumps can prevent waste from collecting in a stagnant area, allowing the organic matter to be efficiently moved and collected in your mechanical filter.

Carbon dioxide is essential for algae to thrive in aquatic environments. Efficient aeration can greatly decrease the amount of carbon dioxide in your system through gas exchange.

As the amount of dissolved oxygen in the water increases in the tank, carbon dioxide is released. This is the aerators job. The amount of aeration needed will depend on the size of your aquarium.


Algaecides, are an option for some types of systems but can be very harmful to others. Typically, algaecides are only recommended for freshwater and saltwater aquariums with no plants or other aquatic invertebrates.

Algaecides can be dangerous for aquatic plants, corals, invertebrates, and certain types of fish that have a low tolerance for copper.

This is probably the last resource for most.

Quickly getting rid of algae

9 steps to follow in order to control and get rid of algae:

1. Make sure you are not overfeeding your fish and remove any waste food from your tank.
2. Reduce the light and reduce the amount of algae that can grow. A tank in direct sunlight is a no.
3. Perform weekly water changes of 10-20% of your aquarium’s water.
4. Clean your tank regularly. Scrub the sides with an appropriate scrubber and siphon the substrate.
5. Maintain your filter. Remember to replace the media.
6. Add some algae eating tank mates.
7. Live plants will reduce algae growth.
8. Keep the water moving and aerated – stagnant water promotes algae growth.
9. Algaecides.

In conclusion: Don’t worry if you experience algae growth in your aquarium. Algae growth in aquariums is manageable and by following the tips in this guide you will be able to remove your unwanted algae.

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