I have set up a new aquarium. I laid aquarium soil as the base with gravel on top. After 1-2 weeks, the white coloured stones are discolouring. Is it algae growth? I’m thinking of replacing the white stones with large ones.

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  • Welcome to pets.SE! I would assume algea growing is usual normal in tanks. So I am not sure if it is in general possible to have white stones staying white... If you have the values of your last water test that may be helpful for the aquarium experts to answer your question more specific :) May 6, 2022 at 11:44
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    so your question is,is the discoloration algae? May 6, 2022 at 13:49
  • @Allerleirauh So, I think its best to switch to black stones.
    – techno
    May 6, 2022 at 17:25
  • @trondhansen Please see my comment below your answer.
    – techno
    May 6, 2022 at 17:26

1 Answer 1


There is two main causes for the discoloration of aquarium gravel.

#1 algae both green and brown algae.

#2 bacteria film,mainly nitrifying bacteria they are often light brown.

The discoloration of your gravel is a sign of a healthy tank,we all want our tank to look beautiful but it takes a lot of work to keep it that way.

Regular cleaning is the only way to keep the gravel and other surfaces in your tank look beatiful but the discoloration of the gravel canot be stopped.

You will need to change the gravel from time to time or you can remove the gravel from your tank and use hydrogenperoxide to remove the discoloration,a lot of work and little effect and you need to dry the gravel fully before adding it back to your tank.

Keeping the nitrogen low will help against algae growth and vacuuming the gravel will keep the bacteria film away/less visible.

  • Thanks for your input.What do you think is the main cause ? and your advice on tackling the same
    – techno
    May 6, 2022 at 17:24

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