How do I know if this is cyano?

[Hyskulhero]

Hi all. I know this is my 2nd thread on algae but search engine's down. I have a brown algae covering my substrate and it's spreading to my rock. How do I know if this is cyano? It's brown colored, not stringy just covering my sand. Should I perform a large water change? Or shorten my light cycle? Clean up crew will arrive in a week. Tank is 3 months old.

[Jake15]

If you have any fish in there then cut back on the feeding a bit. Also you could turn the lights off and do a water change. It doesnt have to be a large one. Just do about 20%. But you'll know for sure if the algea turns red and looks like velvet that it is cyno

[woodstock '69]

It is probably just diatoms that usually show up during the "seasoning" or maturing of a new tank. You said it has been 3 months since set up? and that would be considered "on schedule". They should go away in a few weeks, but like Jake15 said, you should be careful about not overfeeding as well.

Michael

[drummereef]

Brown on the substrate/rock is diatoms. IF the tank is only 3 months old, it is normal for the tank to go through these algae blooms. The cleanup crew will help. Just keep your water parameters in check and it should go away on its own. Using RO/DI water will help too.