Brown algae?

[Oli]

Hi guys, does anybody know what this brown stuff on the rocks and decor could be. Seems to have appeared almost overnight?

 

[Bruce Leyland-Jones]

Looks like brown 'algae', which is actually diatoms.
Does your tank have nitrates? Fish waste? Uneaten food?

It's harmless to fish, although can smother aquarium plants if allowed to get out of hand.
Given that your chosen decor is white, it'll be very, very obvious.
NOTE that this is one algae that does well in low light, so reducing light in your tank will not remove this stuff.

 

[foxgirl158]

This looks like the stuff on my plants. How do you get rid of it? My snail is too big to clean it off.

 

[Slaphppy7]

A good article on the subject:

What Causes Brown Algae in Your Fish Tank?

Struggling with brown algae in your fish tank? Learn effective ways to identify, remove, and prevent it for a cleaner, healthier aquarium.

www.thesprucepets.com

 

[Bruce Leyland-Jones]

The tank has to be properly cycled to the stage where any ammonia is turned into nitrites and the nitrites are turned into nitrates. The brown algae loves nitrates, so a clean tank is essential to limit these. Real plants would also compete with the diatoms for the nitrates and, for real plants, good lighting is a must.
Some fish will enjoy eating this, although if you go this route, please be sure you can fully meet the needs of the fish in all respects.
NOTE as I've already mentioned, brown algae does well in low light and less well in good light, although aquarium plants like the better lighting.