Fishbowl Adviser

How to Control Aquarium Algae

According to some sources, dealing with algae is the number one reason why people give up on having fish tanks. Knowing how to control aquarium algae is essential if you wish to maintain a healthy environment for your fish. However, having algae in your tank isn’t necessarily bad. Read our guide and get familiar with all the things you should know about controlling aquarium algae.

Fish and aquarium algae

Types of Algae in Fish Tanks

Before you start controlling the algae in your aquarium during your regular aquarium maintenance, you have to learn what types of algae you can encounter. We listed the most common ones in the table below so that you can identify them easier and learn how to get rid of them.

Brown (Diatom or Silica) AlgaeIt’s present in aquariums that have Ammonia and Nitrates, and it’s a sign of poor water quality. It can catch on the plants, walls, substrate, etc., as brown dust that can turn into a thick layer.
Green Algae – Coat, Spot, Floating, and FilamentousThere are many types of this algae that you can encounter. Algae Coat is very common, but it can become toxic when in high quantities. Green Spot algae aren’t edible by algae-eaters, and it can cause problems. If the water in your tank turned green, and you’re wondering how to fix a cloudy fish tank, you’re dealing with the Floating type. Filamentous algae won’t be visible if you have algae eaters, but if not, they can spread too.
Red AlgaeDespite the name, these algae are sometimes black, dark brown, or even dark green. They can be very hard to treat since algae-eaters won’t touch them.
Blue/Green Algae (Cyanobacteria)This type isn’t exactly an alga but a bacteria that is able to photosynthesize. It’s not toxic in normal quantities, but it can become fatal for fish if it overgrows. It’s concentrated in places with the most light, and it looks like a brown, reddish, blue, or green slime.

You might find many types of algae in your tank, but the most probable scenario is that one or two are the main culprit for your problems.

What Causes Algae Overgrowth?

Different types of algae overgrowth are caused by different reasons, but the main one always is bad water quality. Now, if you notice that some type of algae is spreading, you must first identify it and then learn what you should do.

A higher quantity of algae appear because of extra nutrients in the water that can be caused by a number of reasons:

  • Too much light
  • Bad filtration
  • Overheating the water
  • Low, high, or fluctuating levels of CO2
  • Too much ammonia and nitrates
  • High phosphates
  • Bad air circulation pumps
  • Lack of oxygen
  • Excess of fish food

The overgrowth can catch everything, from your aquatic plants that can be grown on the sand to the aquarium gravel and decorations on it. It would be a shame to learn how to plant aquarium plants and then let algae cover every herb. Overgrowth can even catch on your floating aquarium plants.

How to Remove Algae from a Fish Tank?

There are ways to save your tank if you’re facing infestation by some type of algae. If you see a small number of algae that caught up on some of your plants or gravel, simply take it out. Trim the leaves of the plant or learn how to clean aquarium gravel that had been infested. Don’t fret too much – having algae in your aquarium from time to time is entirely normal, especially if we’re talking about a fishbowl without filtration. That can be solved with a water change, lowering the amount of light, and some algae eaters.

On the other hand, if the problem has spread out and you’re looking at a tank that turned into a mess, there are a few methods you can try to remove algae.

  • Start with manually removing all the excess algae you can take. Use tweezers or scissors and have gloves on.
  • The next step is cleaning your substrate, decoration, and walls. If you have sand, remove the upper layer.
  • Change the water, even several times if needed. Fifty percent per week is recommended.
  • Check your light bulb and see if it’s adequate for the type of tank you have. See what’s the right amount of light and tune it in.
  • Set up a good filter and suitable air circulation pumps. Your filter should be strong enough to make water flow in the whole tank.

Preventing Algae Overgrowth

It’s always better to be safe than sorry, so prevention is the key to having a healthy ecosystem in your tank. Remember that it isn’t possible to fight the algae itself. The only thing you can do is to fight the cause.

The easiest way to keep everything neat is to clean your fishbowl during water changes and to have strong water filtration with high-quality filter media. That will keep you safe from any imbalance that can happen.

You must learn how to adjust pH in your aquarium, just as you would if you had to acclimate new fish to the tank. This is very important since pH is a crucial indicator that the water quality is good. Find the cause of algae overgrowth by testing your water. Buy a test kit and check your nitrates, phosphates, and ammonia.

After you’re done with setting up a fish tank, make sure you don’t overfeed your fish since the excess of food creates extra nutrients for the algae. Also, control your light level and the water temperature. Too much light and a high temperature will increase the rotting of organic material in the water, which immediately raises ammonia and algae. Controlling the levels of nitrates and ammonia is best done by cycling your fish tank.

Another thing you can do is to get some algae eaters. They can be aquarium snails, several types of fish, or live plants that will use the extra nutrients instead of algae.

Fish and plants in the aquarium


Having algae in your tank is completely normal and very common. The only way that you can face overgrowth and infestation is if you heavily neglect your tank and don’t check water quality. If you notice several algae in the aquarium, just take them out. In case it happens that your whole tank gets infested, make sure you find the cause and follow our guide to get rid of it.


  1. How to Remove Algae from a Fish Tank – Fetch by WebMD
  2. Avoid and Eliminate Green Algae in a Pond or Aquarium – CaringPets


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  1. i am happy i read this post

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