Yeah, I'm not trying to be a terminology stickler or anything, but it is important to know which you have since the treatments for each may vary.
The Tech M is a real relief of a cure for bryopsis, which was one of the hardest for me to rid compared to typical hair algae.
Tech M did nothing to deter common hair algae in my case.
I wasn't disagreeing at all. I just wanted to clarify things for the OP. To my knowledge, Tech M does nothing for Derbesia sp. and similar algal species. It only seems to be effective against Bryopsis, as you say.