What Causes Algae to Grow in Aquarium Plants?

At some point on the service life of most aquariums, an algal bloom will occur and cause problems with keeping fish and aquatic plants alive. Aquatic plants provide benefits for the fish within the aquarium but can provide breeding areas for algae that can starve both the plants and fish of the nutrients they need for survival.

  1. Algae

    • A rapid increase in the amount of algae in an aquatic system is known as an algal or marine bloom. The reasons for a bloom occurring in an aquarium can include an excess of nutrients, such as phosphorous and nitrogen. Problems caused by a large amount of algae within an aquarium include the starvation of plants and fish that rely on the nutrients within the water. When fish and aquatic plants begin to starve, they die and become food for the algae, leading to a larger increase in the reproduction rate of algae.

    Green

    • Green algae commonly affects aquatic plants within an aquarium, with green thread algae often attaching itself to plants for growth. Excessive light levels in an aquarium can spur a glut of green thread algae and green bunch algae. Pelt algae, which attaches itself to the leaves of aquatic plants, grows in water with a high nitrate content and can result in the death of plant leaves. Green spot algae form small green spots on plant leaves and thrive in aquariums with poor water quality or unstable water levels. The introduction of algae-eating fish and snails can reduce the amount of green spot algae in an aquarium.

    Red

    • Newly planted aquatic plants can often bring with them red beard algae, which can grow branches up to 6 inches in length. Red beard algae, often colored dark green to black, are usually found in aquariums with high nitrate levels and carbon dioxide deficiency. As red beard algae attach to plants firmly, they can prove difficult to remove. High nitrate levels and excessive lighting can increase the rate of black spot algae reproduction.

    Blue Green

    • The arrival of blue green algae in an aquarium is associated with high levels of nitrogen and phosphorous, along with high lighting levels. This type of algae is difficult to remove, as most species of algae-eating fish will not eat the algae, although snails can reduce the spread of blue green algae. Sunlight is a major cause of algae growth; you can often clear blue green algae by placing the aquarium in total darkness for five to seven days.