ID on this green film algae?

[taylormaximus]

So this has been growing in my tank for about 4 months now, a deep green film, especially in areas of high light. It grows on the rocks, and the glass but never touches the sand. It also covers right over any corals on the rocks, it killed my bird's nest coral in a matter of weeks after getting completely coated in an almost cobweb like green sheet. It's also killed all of my candy cane corals and my fox coral, growing over top basically any hard structure, so most of my soft corals have been unaffected at least.

Unlike green coralline (which I had previous to this) it can be very easily scrubbed off the rocks with a toothbrush, but it can't be blown off with a turkey baster. When it is brushed off it comes off in large green flecks that almost resemble pieces of nori, which then float around the tank. It actually smells like seaweed as well. And it starts to show signs of returning after 3 days or so. I can provide water parameters or other details if needed, I haven't been able to get a nitrate reading since it's showed up though.

I've tried dosing Razor, which made it grow less aggressively on the glass, but had no effect on the rocks. I've also tried Chemiclean on it twice (in case it's green cyano) with very limited success, it definitely slowed the growth for a few days, but didn't disappear from the rocks until I physically brushed it off, and then it still returned in a few days. My clean up crew largely leave it alone, some turbo snails pick at it a bit, but my tuxedo urchin is the one thing that actually eats it.

I was also able to take a look at it through a microscope, it appears to be a tangled mat of green strings. Any ideas on an ID for this or suggestions to beat it would be amazing.

 

[Mr. Mojo Rising]

Is the tank near a window?
Are there any powerheads in the tank? If a turkey baster blows it off, it can indicate that more flow is needed.

 

[taylormaximus]

Is the tank near a window?
Are there any powerheads in the tank? If a turkey baster blows it off, it can indicate that more flow is needed.

It's across the room from the window, probably only gets about a half hour of indirect light a day, although it is in the kitchen which has bright white lights, I'm not sure if that affects anything, but there's also nothing I could do about that unfortunately.

A turkey baster does not blow it off, but it flakes off very easily with a toothbrush. Otherwise for flow I have one flow pump as well as a HOB filter which provides a decent amount of flow.