The Fish Guru

Diving into Diatoms: Understanding and Managing These Tiny Organisms in Your Aquarium

Understanding Diatoms

Diatoms are a type of unicellular alga that belong to the Bacillariophyceae family. They are characterized by their unique silica cell walls and are known to exist in various shapes and sizes.

These tiny organisms are a crucial component of the ecosystem as they produce almost a quarter of the oxygen we breathe and are significant contributors to the food chain. Additionally, they play a vital role in reducing carbon dioxide levels in our atmosphere.

Importance of Diatoms

Diatoms are a critical component of the environment. They are photosynthetic organisms that use energy from the sun to transform carbon dioxide into organic matter.

During this process, they release oxygen into the atmosphere, thus providing an invaluable service to our planet. Diatoms are also at the bottom of the food chain, with bigger organisms feeding on them.

As a result, any changes in diatom populations caused by environmental events, such as climate change, can have far-reaching consequences on the entire ecosystem.

Harmful Diatoms

While diatoms are essential to the environment, some species can be harmful to the human population. Pseudo-nitzschia is one such diatom that produces a neurotoxin that can cause amnesic shellfish poisoning.

This toxin can accumulate in shellfish, making them unsafe for human consumption. Harmful algal blooms, associated with these types of toxins, are becoming increasingly prevalent all over the world.

Climate change, amongst other factors, has been identified as a leading cause of these blooms.

Diatoms in the Aquarium

If you are an aquarium owner, you will undoubtedly encounter diatoms at some point. Although they are not harmful, they are unsightly and can make your aquarium look unappealing.

In this section, we will explore the causes of diatoms and how you can address them.

Diatoms and Tank Cycle

If you are new to aquarium keeping, you may have experienced what is commonly referred to as the “ugly phase.” During this period, diatoms may begin to grow in your tank, giving it an unpleasant rust-colored coating. This phase is a natural occurrence and will usually disappear once your tank establishes its biological equilibrium.

Causes of Diatoms

The imbalance in nutrients in the aquarium is the most common reason for the sudden growth of diatoms. High levels of ammonia, nitrite, nitrate, phosphate, and silicate can trigger their growth.

However, the main contributor is silicate, which is present in many types of substrate and rocks. While silicate helps to stabilize the pH in your tank, it can fuel the sudden growth of diatoms.

Identifying Diatoms

Diatoms are often mistaken for brown algae, but they belong to a separate group known as the Dinoflagellata superclass. They are brown or rust-colored and form a thin film that adheres to surfaces in your tank.

Preventing Diatoms

To prevent diatoms from taking over your tank, you must keep your aquarium clean and maintain the appropriate nutrient balance. Perform regular water changes, limit feeding, and avoid using silicate-rich substrates and rocks.

Additionally, consider investing in a UV sterilizer, which can help to prevent diatoms from growing in your tank.


In summary, understanding diatoms is crucial to the environment, and, as aquarium owners, we must learn how to manage their growth. By learning about the causes of diatoms, how to identify them, and how to prevent them in our tanks, we can ensure that our aquariums remain healthy and visually appealing.

Diatoms are an essential component of the ecosystem, and maintaining their populations is essential to the well-being of our planet. Diatoms Vs. Dinoflagellates

Diatoms and Dinoflagellates are two types of unicellular algae commonly found in aquatic environments.

Hence, it is essential to know how to differentiate between them since they have different physical structures that require different care procedures.

Difference between Diatoms and Dinoflagellates

Diatoms and Dinoflagellates differ significantly in their appearances. Diatoms appear elliptical or circular and have a silica cell wall with pointed ends, giving them a distinct box-like appearance when viewed under a microscope.

On the other hand, Dinoflagellates are rod-shaped in appearance and have two flagella that they use to swim.

Differentiating Diatoms from Dinoflagellates

To differentiate Diatoms from Dinoflagellates, you need to collect a water sample and filter using a coffee filter. The filter will capture the larger cells that you can view under ambient light using a microscope.

Once you have the sample, note the shape of the cells; if they have an elliptical or circular shape, they could be Diatoms. However, if the cells are rod-shaped with two flagella, they are likely Dinoflagellates.

Removing Diatoms

There are several reasons why you may decide to remove Diatoms from your aquarium. One of the reasons is an imbalance in the tank.

Diatoms can bloom when there is a nutrient imbalance in the ecosystem. Additionally, the overgrowth of Diatoms can cause corals to choke, resulting in the death of your precious aquatic plants.

Diatoms can also deplete the nutrient levels in your tank, starving other beneficial microorganisms like bacteria.

How to Remove Diatoms

To remove Diatoms from your aquarium successfully, you must correct the water parameters. Make sure you measure the nutrient levels in your tank regularly and keep them in check.

You can also consider adding new rocks or substrates to your aquarium that do not contain silicates or phosphates, which are the main nutrients that Diatoms require to survive. Physical removal is another effective way of getting rid of Diatoms from your tank.

Use an aquarium vacuum or scrubber to make sure you remove the excess Diatoms from the surfaces in your tank.

Preventing Diatoms

To prevent Diatoms, it is crucial to ensure that you have a good water source and practice good aquarium maintenance habits. Test your water source regularly and invest in a Reverse Osmosis De-Ionization (RODI) system that will purify your water before you add it to the aquarium.

Practice regular water changes to maintain the appropriate nutrient balance. Additionally, consider investing in a UV sterilizer, which can help to prevent Diatoms from growing in your tank.


In conclusion, Diatoms and Dinoflagellates are types of algae that can inhabit your aquarium and affect the overall ecosystem. Therefore, it is crucial to differentiate between these different types of algae and to understand how to remove them from your aquarium should you notice a Diatom overgrowth.

By controlling the nutrient levels in your aquarium, practicing good aquarium maintenance habits, and investing in tools like scrubbers and UV sterilizers, you can prevent Diatoms from growing in your tank. In conclusion, understanding Diatoms and Dinoflagellates is crucial to maintaining a healthy and balanced aquatic environment.

Diatoms are essential to the ecosystem, producing oxygen and serving as food sources for larger organisms, but they can overgrow and cause harm to your aquarium’s ecosystem. Proper identification is necessary before any removal procedures are undertaken.

However, preventive measures, such as regular aquarium maintenance, using the correct water source, and investing in a UV sterilizer, can limit the overgrowth of Diatoms. Overall, the importance of maintaining a healthy aquatic environment cannot be overstated.

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