Looks very much like my Hair algae (filamentous algae) except for the tan color. I have done 8 50% wc and there's still some around, but it's not spreading.
There is something out of whack with my tank that's causing this algae. I have to control it using Amano shrimp, manual removal, or whatever it takes until I can correct the parameters that are off. Something is definitely going on in the tank. A lot of the plants have stopped growing, which leads me to think that something the plants need, like ferts or Equilibrium, is off. I have to go over my calculations for the dose again.
I think your algae crumbling at touch is a very good sign that the algae is dying.