My Plants & Tank Have Dark Algae

Dark algae causes aquarium owners to emit groans of frustration. It happens in every tank, no matter how clean the water is, and there is no safe way to completely prevent its growth without harming the living organisms inside the water. A variety of algae types exist, and several look like algae but are not. Healthy algae is green and has a hair-like appearance about it -- a frustrating, but telltale sign of a healthy aquarium. There are several ways algae can be managed in a tank.

  1. Lighting

    • Since algae is a basic organism, it needs light to survive and grow. By reducing the light received by the aquarium, including natural light from windows, dark algae growth can be reduced. Place your tank away from windows and have the aquarium lights on a timer, with six hours of light every day, for any fish in your tank require repetitive light schedules.

    Cleaning Tank

    • When cleaning your tank, leave a small section of algae in the tank. Many tank owners have the urge to clean the entire tank, leaving no algae behind, however, this causes faster new growth of the basic organism. Leaving a small patch of algae behind when cleaning causes it to absorb some of the nutrients in the tank, not allowing new growth because there is not enough food for it.

    Feeding

    • Do not overfeed the fish or plants in an aquarium. This can add excess nutrients to the water which provides food for the algae. This also applies to any fish or plants that die as well -- they decay and provide nutrients for dark algae to feed on -- so they must be removed as soon as they are spotted.

    Cyanobacteria

    • Commonly dark in appearance, cyanobacteria looks like algae but is not the same as the basic primitive green plant. The bacteria is easy to take out of the tank once it has been spotted, however, it will grow back almost overnight and is very difficult to control. The tank must be emptied and cleaned thoroughly, as well as all the plants rinsed and cleaned off. The light near the tank is reduced for several weeks and organic chemicals, available at local aquarium stores, can be added to the new water to keep the bacteria from returning.