Recurring Algae in an Aquarium

Algae is a natural part of an aquarium's ecosystem, and will grow even in well-maintained tanks. Small quantities of algae, particularly green algae, are not dangerous. Algae is closely related to plants and can break down aquarium waste. However, an overgrowth of algae can cloud the water in an aquarium and rob plants and fish of nutrients and oxygen. Recurring algae that grows in large quantities is typically a result of poor husbandry and can be remedied with minor alterations in the aquarium's ecosystem.

  1. Oxygenation

    • Blue-green algae, which is a cyanobacteria, thrives in low-oxygen environments. It typically grows at the surface of the water or attached to plants, and is named for its blueish-green tint. Add an air stone to your aquarium to provide proper oxygenation. This is especially important for aquariums that are fully covered and don't have much oxygen circulation. Even if the algae continues to grow, the harm it causes is minimized by increased oxygenation from the air stone. For additional oxygenation, consider adding edible aquatic plants to your aquarium.

    Stagnant Water

    • Many varieties of algae grow best in stagnant water. Large tanks with only minimal filtration are particularly susceptible to these varieties of algae. Maximize water currents by adding a waterfall in the middle of the aquarium or increasing the number of water filters. Increased filtration may also help to filter out wastes and nutrients that encourage algae growth.

    Light

    • Fish need light in to thrive, and many fish owners leave lights on in their aquariums all day. Because algae grows best when exposed to light, this practice can prove problematic. Put aquarium lights on a timer and leave lights on for a maximum of 10 to 12 hours each day.

    New Tank Syndrome

    • Newly-established fish tanks are especially susceptible to an overabundance of algae. This problem usually resolves itself as the aquarium becomes settled and establishes its own ecosystem. In the meantime, use an algae scraper to remove algae buildup on tank ornaments and glass.

    Water Changes

    • Changing the water too frequently or too infrequently can cause algae. Change 25 percent of the water in your aquarium every one to two weeks, depending on water clarity. Changing too much water too frequently can disturb the ecosystem in the aquarium, resulting in new tank syndrome and algae growth. Infrequent water changes, conversely, encourage the buildup of wastes upon which algae feed.