What is this algae, how do I prevent

[jeffruth]

Hello. So I have been letting this side of the tank go in order to see what comes of it. It has algae? on it. It seems to be turning red. Thoughts?

 

[brendenscott]

That is GDA green dust algae. Too much light or not enough co2 possibly. Actually good to let it go like you did. Best to wait a good 3 weeks then scrape all off at once then do large water change. If you just keep scraping it off, it just goes back in the water column to find another part of the glass to chill on.

 

[brendenscott]

It turning red is actually a good thing. That usually means it’s dead. Just scrape the dead off.