How to Get Rid of Diatom Blooms

How to Get Rid of Diatom Bloom In An Aquarium

If you have been keeping an aquarium for any length of time, you know that it can be an art and a science. At some point, you will most likely experience the formation of a diatom bloom. While not incredibly difficult to get rid of, they can be a nuisance.

What Is A Diatom

So what is diatom algae, exactly? Diatom algae (sometimes also called “brown algae) are naturally occurring organisms that can occur in either freshwater or saltwater environments. They can and do also inhabit rock or sand and can even live in the glass walls and floor of your aquarium, which is frequently how they enter your tank environment in the first place!

Can Diatom Algae Be Harmful To Fish And Coral

We know that diatom algae, appropriately controlled and in moderation, can be a healthy addition to your aquarium ecosystem. But can diatom algae be harmful to fish and coral? The answer to this question is not a straightforward yes or no. It depends on the occupants of your tank and how they interact.

Diatom algae itself is typically harmless and can even be beneficial to your aquarium by producing oxygen and serving as a food source for some aquatic species. However, a sudden increase in the diatom algae population can also signal imbalance within your aquarium, particularly when it comes to the concentration of nitrates or phosphates.

In most cases, the time when you are most likely to see a diatom bloom is when you are first starting a new aquarium ecosystem. You have just added new sand, rock, plant life, water, and aquatic species, and there is a “settling period” the tank itself goes through to find its balance.

Sometimes you will also see a diatom bloom if your diatom filter has been clogged, your tank lighting is old or too weak or you aren’t using the right filter.

Diatom algae are not generally harmful to fish but can be harmful to live plants and coral. Some species do what is called “encrusting,” which means they will grow on the outside of the plant or coral and create a crust that blocks their host from getting food and respiration. If you see your plants or coral starting to die off, this is a clear sign of encrusting.

What Does Diatom Eat

So what causes diatom algae to bloom? What does diatom algae eat? These are the questions you will need to answer to troubleshoot the source and growth of a diatom bloom inside your tank and gain control over it.

Silicates, a naturally-occurring salt that contains silicon and oxygen, are one of the diatom algae favorite food sources. If you have a layer of sand or rock in your aquarium, you also have silicates in your aquarium. The same holds true for some water sources. Some water naturally has silicates in it. Silicates can also leach into the water inside your aquarium from the glass walls and floor of your tank.

The more silicates are present in your tank, the more the diatom algae will have to eat, and the faster they will multiply.

How To Get Rid Of Diatom Algae

So now the question becomes, how to get rid of diatom algae before it becomes an aquarium problem? Luckily, learning how to get rid of diatom bloom conditions is actually pretty easy!

Let’s take a look at each strategy for how to get rid of diatom bloom algae separately.

Water Changes

If your water has high silicate levels, you may need to switch your water source to control algae. Use pure RO/DI water and perform regular water changes.


Snails love to eat algae! Some of the best snails for algae control include Astrea snails, turbo snails, margarita snails (cold water), Cerita snails, trochus snails, Nassarius snails and, conches.


Sometimes the quickest and best way to control a runaway bloom is to use chemicals. As a side benefit, many aquarium chemicals are formulated to take care of several species of algae in addition to diatoms. Tetra Algae Control is an example of a product that can both treat existing blooms and prevent them from recurring.

Diatom Filters For Aquariums

Using a diatom filter or a Protein Skimmer is one of the best ways to control diatom algae blooms. A diatom filter can remove particles as small as 2 microns (a single human hair is 75 microns!).

For a squeaky clean, brilliant tank that stays that way, you can’t do better than diatom filters.


Diatoms are not harmful, per se. In fact, living diatom algae is said to produce up to 20 percent of the world’s oxygen supply! More importantly for the overall health and balanced ecosystem inside your tank, diatom algae can serve as food for some species of aquatic life, including mollusks and small crustaceans. So in theory, you actually want to maintain some level of diatom presence in your tank ecosystem for the health of all species inside your aquarium.

We hope this expert article has helped increase your knowledge of what diatom algae is, its beneficial and detrimental qualities, its purpose for existing in your aquarium ecosystem and how to keep its presence in balance with other aquatic life.

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