I Have Algae Growth on My Glass Tank Cover

Algae is a plant-like life form that grows in areas where there is water, light and nutrients. A small amount of green algae growing in a fish tank or on the cover is fine and usually means that your tank has the means to support life on its own. Green algae that is confined to the rocks and decorations in your tank not only add character, but shouldn't be worrisome. However, if the algae is thick, hair-like and taking over your tank, cover, or turning the water green, you need to control the growth.

Things You'll Need

  • Timer
  • Algae-cleaning sponge
  • Algae-eating fish
  • Aquarium net
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Instructions

    • 1

      Remove the tank from major sources of lighting. If your fish tank is sitting next to a window, even if it receives little sunlight, algae will grow more rapidly on both the tank and the lid compared to a tank away from a window. If it is required that your tank be near a window, it is extremely important to keep blinds or curtains shut during the day to control algae growth.

    • 2

      Set a timer to allow for eight hours of light in your tank within a 24-hour period. When turning your light off, be sure that it is at the same time of the day so that your fish become accustomed.

    • 3

      Change 20 percent of water in the tank.

    • 4

      Control the nutrients that are put into your tank. Because most of the nutrients (nitrogen, phosphorus, potassium) come from fish waste, excess food, plant debris or other organic materials, it is important that you do what you can in order to lower these levels. Do not overfeed your fish. Overfeeding will lead to extra food floating around, adding more nutrients to the water which could increase the rate at which algae grows.

    • 5

      Clean the glass and lid less often. As contradictory as it sounds, algae will grow back faster in a clean tank. This is because when no algae is left behind, the nutrients are available to new algae as there is no competition for these nutrients. If you were to leave even a small amount of algae, the nutrients are used up, and algae grows more slowly. When you do clean the glass, use an algae-cleaning sponge available at most pet stores.

    • 6

      Add some algae eating fish. A few Plecostomus fish species will help to control the levels of algae (along with the listed methods). For marine aquariums, there aren't many options that will keep the tank clean without falling prey to other fish in the tank. However, parrotfish and blennies will eat some the algae, but not a significant amount, so it is important to still keep a close watch.

    • 7

      Remove dead fish with a net as soon as you notice them. Dead, decaying fish increase the level of alage nutrients in the water and will create the ideal environment for algae growth.