What Is Brown Algae (Diatoms)

Brown algae, often referred to as diatoms, are a group of photosynthetic organisms falling within the larger class Phaeophyceae. Unique to their kind, their cell walls, called frustules, are composed of hydrated silica, enhancing their structural robustness.

Primarily, brown algae inhabit marine environments, although freshwater variants exist. They showcase a rich diversity, ranging from microscopic, unicellular diatoms to macroscopic forms, like the towering kelps. This divergence stems from the evolutionary adaptability of diatoms.

Importantly, diatoms are characterized by their brown or golden-brown pigmentation. This distinctive color results from fucoxanthin, a pigment that complements chlorophyll a and c in their photosynthetic apparatus. Its presence is a defining feature of the group, differentiating them from green algae.

The life cycle of brown algae encapsulates a mix of sexual and asexual reproduction. In the asexual phase, diatoms divide into two, with each daughter cell retaining a frustule half. Successive divisions can reduce diatom size, which is eventually restored via sexual reproduction or auxospore formation.

Brown Algae Vs. Green Algae

Brown algae’s unique coloration results from the presence of the pigment fucoxanthin. It overlays the green of chlorophyll, imparting a characteristic golden-brown hue. In contrast, green algae lack fucoxanthin and predominantly contain chlorophyll a and b, hence their green coloration.

Their cell structures differ notably. Brown algae possess siliceous cell walls or frustules, offering enhanced structural stability. Green algae, on the other hand, have cellulose-based cell walls, similar to terrestrial plants.

Habitat preferences also differentiate these two groups. Brown algae are mostly marine, though some inhabit freshwater. On the other hand, green algae are more versatile, residing in fresh water, salt water, and even on land in moist conditions.

Excessive Nutrients

In a balanced ecosystem, nutrients are regulated through the food chain. However, when nitrate and phosphate levels rise, it often leads to an algal bloom. The surge can stem from overfeeding, decaying organic matter, or insufficient water changes in an aquarium setting.

Nitrate is typically the end product of the nitrogen cycle in an aquarium. While beneficial bacteria convert harmful ammonia and nitrite into less toxic nitrate, excessive nitrate can still cause issues. High nitrate levels often encourage diatom growth, especially when combined with other conducive conditions.

Phosphate, on the other hand, often enters the system through fish feed and tap water. While small amounts are necessary for plant and fish health, high phosphate levels can spur diatom proliferation. Phosphates can also limit the growth of green algae, giving an upper hand to brown algae in the competition for resources.

Lighting Conditions

Brown algae are generally well-adapted to low-light conditions. The presence of fucoxanthin, their primary accessory pigment, allows them to efficiently absorb the blue-green light, which penetrates deeper into water bodies. This adaption to low light often leads to their domination in darker, deep-water environments.

In aquariums, inappropriate lighting conditions can lead to diatom blooms. An extended photoperiod, the duration of light exposure, can fuel excessive growth. Conversely, inadequate lighting may limit the growth of competing green algae, providing an advantage to diatoms.

The light spectrum also matters. Light in the blue-green spectrum can favor diatom growth due to the fucoxanthin’s light absorption property. Hence, aquarium lights catering more to this range might inadvertently promote brown algae.

New Tank Syndrome

When a new aquarium is set up, it takes some time for the ecosystem to stabilize. The nitrogen cycle, an essential biological process breaking down harmful waste products, has yet to be established. This period is characterized by fluctuating water parameters, including nutrient levels.

Elevated levels of silicates, nitrates, and phosphates are commonly observed in new tanks. These nutrients can leach from substrate and decor materials or can come from tap water. They provide the perfect nourishment for diatoms to thrive, leading to rapid, excessive growth.

Additionally, the lack of established competition in a new tank environment favors diatom bloom. With few or no algae-consuming organisms and limited competing algae species, diatoms get an unobstructed chance to proliferate.

Effects on Aquatic Life

Many small fish and invertebrate species, like certain shrimp and snails, feed on diatoms. Their scraping or filtering feeding techniques allow them to consume these algae, providing a valuable nutrition source. For these creatures, a moderate diatom presence can enhance diet diversity.

However, when diatoms grow out of control, becoming a dominant feature in your aquarium, they may start causing harm. For instance, if they cover large areas of plant leaves, they can inhibit the plants’ photosynthesis process by blocking light.

Fish may also be affected indirectly. Dense diatom blooms can lead to oxygen depletion, especially at night when photosynthesis ceases, but respiration continues. This may stress the fish, impacting their health and behavior.

Invertebrates that rely on shell or exoskeleton formation can also face challenges. Diatoms utilize silicates for their growth. If diatoms proliferate extensively, they may deplete the silicate levels in water, potentially affecting the shell growth of certain invertebrates.

Aesthetic Impact

When diatom infestations occur, they often manifest as a brownish coating on various surfaces. This can include aquarium glass, decorations, substrate, and plant leaves. The extent of the coverage can range from light dusting to thick, noticeable layers.

This brown, often slimy layer can greatly disrupt the vibrant colors and clear view that aquarium hobbyists strive for. The algae can obscure the viewing pane, making the fish and plants within less visible and marring the overall aesthetics.

Moreover, if left unchecked, brown algae can envelop aquarium plants, masking their natural color and inhibiting photosynthesis, causing them to appear unhealthy. The algae can also cover decorative elements, diminishing their visual contribution to the aquarium’s aesthetic.

Regular Maintenance

Water changes are vital for diluting excess nutrients like nitrates and phosphates, which fuel diatom growth. Typically, a weekly change of 10-25% of the tank’s water volume is recommended. This can help keep nutrient levels in check, curbing the potential for a diatom bloom.

The process involves removing a portion of the old tank water and replacing it with dechlorinated, clean water. Care should be taken to match the temperature and pH of the new water with the existing aquarium conditions to avoid stressing the inhabitants.

Substrate cleaning is another crucial maintenance task. Decaying organic matter, like uneaten food and plant debris, can accumulate in the substrate and release nutrients as they break down. This can create an ideal environment for diatoms to thrive.

A gravel vacuum or siphon can be used to clean the substrate. This tool not only removes debris but also siphons off a portion of the water, aiding in the water change process. Regular substrate cleaning can help maintain a clean, nutrient-balanced environment, discouraging excessive diatom growth.

Correct Lighting

The intensity of the light should be appropriate for the aquarium’s size and the needs of the plants and animals within. Too much light can encourage algal growth, while too little might inhibit the growth of beneficial algae and plants, giving diatoms an advantage.

The duration of lighting, or photoperiod, is also important. A common recommendation for aquariums is 8 to 12 hours of light per day. Extended periods of light can promote diatom growth, while too little light can stress the aquarium’s inhabitants.

The spectrum of light also matters. As diatoms are more efficient at using the blue-green spectrum for photosynthesis due to the presence of fucoxanthin, a light source that overly caters to this range might favor diatom proliferation.

Modern aquarium lights often come with adjustable settings for intensity and spectrum, and some even have built-in timers to regulate the photoperiod. These features can help you fine-tune the lighting conditions to maintain a healthy, diatom-free aquarium.

Nutrient Management

As diatoms utilize nitrates and phosphates for their growth, elevated levels of these nutrients can fuel their proliferation. Hence, maintaining optimal levels is key. Aiming for nitrate levels below 10 ppm (parts per million) and phosphate levels below 0.05 ppm can generally help curb diatom growth.

The first step in nutrient management involves regular testing of water parameters. Using an aquarium test kit, you can monitor nitrate and phosphate levels and make adjustments as necessary. Routine testing can provide early warning signs of potential issues.

Preventing nutrient build-up often involves several practices. Avoiding overfeeding, as excess food can decay and release nutrients, is one. Using high-quality fish food that is easily digestible can also minimize nutrient waste.

Additionally, regular water changes can help dilute excess nutrients. Incorporating live plants in your aquarium can also help. They consume nitrates and phosphates for their growth, thus competing with diatoms for these nutrients.

Utilizing Algae-Eating Species

Certain species of fish, snails, and shrimp are known to consume diatoms, making them beneficial additions to an aquarium dealing with a diatom bloom. For example, Otocinclus catfish and certain species of plecos are adept at grazing on algae, including diatoms, from surfaces.

Among invertebrates, nerite snails and amano shrimp are noted for their algae-eating habits. They can help keep diatom populations in check, along with adding diversity to your aquarium.

However, it’s important to ensure that the chosen species are compatible with the other tank inhabitants and the overall conditions of the aquarium. Each species has unique care requirements, including temperature, pH, and social needs.

While biological control can be an effective method to combat diatoms, it should not be relied upon solely. These organisms can’t eradicate a severe infestation single-handedly. Biological control should be part of a comprehensive diatom management plan, complementing other strategies such as regular maintenance, nutrient management, and appropriate lighting.

Manual Removal

Manual removal of diatoms involves physically scrubbing the algae off the surfaces they colonize. This can include aquarium glass, decor, and even plant leaves. A range of tools can be employed for this task, including algae scrapers, scrubbing pads, or a clean toothbrush for delicate areas. For optimal results, remove the decor from the aquarium for thorough cleaning.

For removing diatoms from the substrate, a gravel vacuum or siphon can be an excellent tool. This device allows you to clean the substrate without removing it from the tank entirely. By gently stirring the gravel or sand, you can dislodge the diatoms, allowing the vacuum to remove them along with a portion of the water.

When physically removing diatoms, it is crucial to also address the conditions that led to their growth. This can include nutrient imbalances or poor lighting conditions. If these are not addressed, diatoms may rapidly recolonize the cleaned surfaces.

Chemical Treatments

Chemical treatments often involve the use of algaecides, substances that kill or prevent the growth of algae. While these can effectively reduce diatom populations, they should be used as a last resort due to their potential impact on the aquarium ecosystem.

Before resorting to chemical treatments, it’s crucial to address the root causes of the diatom bloom, like excessive nutrients or poor lighting. Without addressing these issues, diatoms may quickly reappear after treatment.

It’s also critical to follow the manufacturer’s instructions when using chemical treatments. Overdosing can harm or even kill the aquarium’s inhabitants. Additionally, after using an algaecide, a follow-up water change is often recommended to remove dead algae and any residual chemicals.