Red filamentous algae

[Pacman100]

I have this algae growing in my tank in spots, and it is relatively slow growing but starting to spread more and more. It is extremely strong; it can be cut with scissors but cannot just be removed from the rock. Nothing seems to eat it.

I've tried manual removal but it grows right back. I've got a sump with cheato growing but the red stuff still keeps going.

Anyway, an ID and approach to controlling it would be much appreciated.