Tank going through Algae Phases can you ID this for me?

[ASIN28]

Hey all I have a few questions this time around. Tank has been up and running for about 4 months now. I do regular water changes, I’ve noticed this algae that forms in circles all over the back glass.
What type of algae is this?
Also the sand bed stays pretty clean due to my diamond watchman goby who is going to sift himself to death one day lol. From what I understand it’s not a good idea to disturb a decently deep sand bed but I’m starting to get this algae that I see under it through the front glass can I go down in there and clean that?
Last but not least, why do I keep getting what appears to be a film on the top of the tank?
Thanks in advance

 

[TheShrimpNibbler]

I recognize the algae on the walls, but I’m not sure what it’s proper name would be. To get the algae on the side below the sand bed, you could just slide a credit card between the sand and side of the tank. That wouldn’t really disturb the sand bed. The film on the top of the water forms when you don’t have much surface agitation.