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SESK: Stuff Everyone Should Know · sesk.info/fish-algae-reduce-light

Green algae keeps growing on the glass. What change does a Wisconsin 4-H guide suggest?

Remove the algae and reduce the light.

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  1. Reduce the light ✔
  2. Add more fish
  3. Leave the light on longer

Why: The Wisconsin 4-H guide says this fine green growth is caused by too much light, and that algae should be removed and light reduced.

Huh, didn't know that: Merck says live plants help limit algae by soaking up nutrients that would otherwise feed it.

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What's a fish's favorite kind of math? Al-gae-bra.
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References

Answer: Reduce the light. The Wisconsin 4-H guide says this fine green growth is caused by too much light, and that algae should be removed and light reduced.

  1. University of Wisconsin Extension 4-H: Aquarium Fish (4H369G) fyi.extension.wisc.edu/wi4hpublications/files/2015/10/4H369G.pdf
    This fine, green plant growth is caused by an excess of light. Algae should be removed and light reduced.
    Checked 2026-10-11.
  2. Merck Veterinary Manual: Providing a Home for Fish www.merckvetmanual.com/all-other-pets/fish/providing-a-home-for-fish
    Aquatic plants also help prevent the growth of algae by absorbing nutrients that would otherwise feed the algae.
    Checked 2026-10-11.

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