Algae Id Please

[cracker]

I have this stuff on the back & side walls some on the rock as well it's brown in color & there are a 'few" bubbles. I can get a better pic I think if needed. Thanks

 

[jsker]

Does if fade when the lights are out? Is it a reddish brown?

 

[cracker]

Hello jsker How are things down south ? It looks brown to me no reddish tint. it is slippery to the touch and flakes off when scraped. picture finely crunched up flake food . Can't really see much difference in lights on or off.
The flash from my camera made it look like more than really there. I will check back after lights out to see if there is fading just to make sure.
Ok 10:30pm now not fading really. Uv's are still on though.