How to Remove Brown Algae (Diatoms) in Your Fish Tank

Brown algae, also known as diatoms, are a common nuisance for aquarium enthusiasts. These microscopic, single-celled organisms can quickly take over a fish tank, covering surfaces with a slimy, brown coating. Although they are not harmful to fish, they can be unsightly and indicate underlying issues in your tank’s environment. This article will explore the causes of brown algae growth, preventive measures, and effective methods for eliminating these persistent diatoms from your fish tank.

In this article, we’ll go over:

What is “Brown Algae” (Diatoms)?

Understanding the nature of brown algae, also known as diatoms, is not just a matter of interest but a crucial aspect of effective aquarium care. These single-celled algae, characterized by their brownish coloration due to the pigment fucoxanthin and silica-based cell walls, thrive in nutrient-rich environments. They often find their way into your tank through tap water, substrate, or decorations, where they can quickly take over if not properly managed. 

aquarium plants

While brown algae are generally not harmful to fish, their unsightly brown coating on surfaces like glass, substrate, and plants can be a cause of concern for fish tank owners. This slimy coating, a common sight in freshwater and marine aquariums, clearly indicates an environment that favors diatom growth. Understanding the causes and taking preventive measures can help you maintain a clean and healthy tank.

What Causes Brown Algae (Diatoms)?

Presence of Silicates and Nutrients

Brown algae, or diatoms, thrive in environments where specific conditions favor their growth. One primary cause is the presence of silicates in the water. Silicates are essential for diatoms to build their silica-based cell walls, and these can be introduced into an aquarium through tap water, certain types of substrate, or decorations that leach silicates over time. 

High levels of nitrates and phosphates, often resulting from overfeeding, fish waste, and decaying organic matter, also contribute significantly to the proliferation of brown algae. These nutrients provide a rich food source for diatoms, allowing them to grow and spread rapidly across tank surfaces.

Lighting and Tank Stability

Another contributing factor is the lighting in the aquarium. Brown algae tend to flourish in low to moderate light conditions. In newly set up tanks, a phenomenon known as 'new tank syndrome' occurs, where the environment is still stabilizing, and diatoms are often among the first organisms to colonize these tanks. This can lead to an initial surge in brown algae growth. Insufficient lighting can exacerbate the issue, as diatoms can outcompete other algae types requiring more light. 

Additionally, improper maintenance practices, such as infrequent water changes, inadequate filtration, or overfeeding, can accumulate nutrients and silicates, creating an ideal environment for brown algae to thrive. Addressing these factors through careful water quality management, proper lighting, and regular tank maintenance is essential to prevent and control brown algae outbreaks.

Understanding Brown Algae and Its Effects

Brown algae, or phaeophyceae, are mostly marine algae in coastal waters. Generally, brown algae are not harmful. They are crucial in aquatic ecosystems, providing food and habitat for marine organisms. Some brown algae, like kelp, are even harvested for their beneficial compounds, such as alginates, used in food, pharmaceuticals, and other industries. 

However, excessive growth of certain types of brown algae can indicate ecological imbalances. It may contribute to the overgrowth of harmful algal blooms, which can deplete oxygen in the water and harm marine life.

aquarium tanks

Preventive Measures to Get Rid of Brown Algae Permanently

1. Regular Water Changes

Regular water changes are not just crucial but proactive for maintaining a healthy aquarium and preventing brown algae growth. Aim to change 10-20% of the water weekly. This helps dilute and remove excess nutrients and waste products that can fuel algae growth. Use a gravel vacuum during water changes to clean the substrate effectively, as debris and uneaten food can contribute to nutrient buildup. Consistent water changes help control algae and support the overall health of your aquatic ecosystem.

2. Adjust Lighting

Lighting plays a significant role in algae growth, and understanding this can make you feel more in control and responsible for your aquarium. Limit your aquarium lighting to 8-10 hours a day to mimic natural light cycles and prevent algae from getting too much light exposure. Ensure the intensity of the light is appropriate for your tank’s needs. High-intensity lighting or prolonged exposure can stimulate algae growth. Consider using timers to regulate the lighting schedule and avoid leaving lights on for too long, especially if your aquarium is prone to algae issues.

3. Avoid Overfeeding

Overfeeding is a common problem that leads to nutrient overload in the aquarium. Feed your fish only what they can consume within a few minutes. Excess food decomposes and increases the levels of nutrients like nitrates and phosphates in the water, creating a favorable environment for algae. By controlling the amount of food given and removing any uneaten food promptly, you can reduce nutrient levels and prevent brown algae from thriving.

4. Use RO/DI Water

If tap water contains high levels of silicates or phosphates, it can contribute to algae growth in your aquarium. Use reverse osmosis/deionized (RO/DI) water to lower these levels. RO/DI water systems remove impurities and excess nutrients from the water, making it less likely to promote algae growth. This change can significantly improve water quality and help maintain a balanced aquatic environment.

5. Introduce Algae-Eating Species

Algae-eating species can be valuable allies in controlling brown algae. Species such as nerite snails, otocinclus catfish, and certain types of shrimp are known for their algae-consuming habits. Adding these creatures to your aquarium can help manage algae growth naturally. Be sure to choose species compatible with your existing tank inhabitants and provide the appropriate environment and food for them to thrive.

Aquarium

6. Maintain Efficient Filtration

A high-quality filtration system is essential for keeping your aquarium water clean and containing excess nutrients. Ensure your filter is appropriately sized for your tank, and clean it regularly to maintain efficiency. A well-maintained filter helps remove organic waste and debris that can contribute to algae growth. Consider using additional filtration media designed to remove specific pollutants if necessary.

7. Utilize Algae Control Products

If brown algae persist despite your efforts, chemical treatments designed for algae control can be effective. Products like algae removers or inhibitors can help manage and reduce algae growth. However, use these products cautiously and according to the manufacturer's instructions to avoid disrupting the balance of your aquarium’s ecosystem or harming its inhabitants.

8. Monitor and Adjust Water Parameters

Regularly testing and monitoring your aquarium water parameters is crucial for preventing brown algae growth. Check levels of ammonia, nitrite, nitrate, and phosphate regularly. Keeping these parameters within recommended ranges helps maintain water quality and prevents conditions that favor algae proliferation. Adjust water parameters as needed to address imbalances and create a less favorable environment for algae.

9. Add More Live Plants

Incorporating more live plants into your aquarium can help combat brown algae. Plants absorb nutrients such as nitrates and phosphates from the water, which reduces the amount of food available for algae. Additionally, healthy plants compete with algae for light and resources, helping to suppress algae growth. Choose various fast-growing and hardy plants suited to your aquarium’s conditions to enhance your tank’s natural balance and improve water quality.

aquatic life

People Also Ask

How to get rid of brown diatoms in a fish tank?

If they are on more challenging surfaces like rocks and stones, use a toothbrush or wire brush to scrub them off. After removing as much of the brown algae as possible with a gravel vacuum or other siphon, remove the remaining algae and debris from the tank.

Why do I have brown algae in my fish tank?

Generally speaking, there are a few primary causes: abundant nutrients and too much silica or nitrate in the water. An aquarium may accumulate silica due to tap water containing high levels of silicic acid. Additionally, some substrate types you might be using, like silica sand, may allow it to leach.

How long do brown diatoms last?

Diatoms are particularly prevalent in newly planted aquariums during the first few weeks of ownership. Fortunately, diatoms usually disappear on their own after the plants settle in, and the tank biologically matures over three to four weeks, even in planted tanks with constant silicate levels.

Conclusion

Dealing with brown algae in a fish tank requires a combination of preventive measures, manual removal, and maintaining a healthy tank environment. By understanding the causes of diatom growth and implementing the strategies outlined in this article, you can effectively control and eliminate brown algae from your aquarium. Remember that patience and consistency are key; with time and effort, you can achieve a beautiful, algae-free tank that showcases your aquatic pets and plants at their best.


You may also like

View all
Example blog post
Example blog post
Example blog post