Update:
Well, it's pretty obvious the Mexican Turbos aren't eating this stuff (and neither is anything else). The weekly rock scrubbing in buckets is keeping the rocks much nicer but it's stirred up enough that didn't get siphoned out and now the stuff is all over my sand and glass. Nothing is touching it.
Yesterday I put in a dose of the AlgaeFix and I'll follow those directions and see what comes of it. If that doesn't work I'll put my corals in a quarantine tank and black out this tank until all the algae is dead and try to manually remove everything from the rocks with corals over time.
Can't think of anything else to do. Almost a year of this is making me think a tear down and rebuild could be the way to go. Poor corals though if I have to do that.