Well, M2 will kill it, EM is the generic antibiotic(Erythromyacin).
But..........it does not prevent it from returning or addresses the issues of why you had it to begin with.
I must be very strange to to old mythologist, I use algae as test kits.
AB mentioned high organics and NO3, mostly in negleted tanks, non CO2 methods.
In CO2 enriched tanks, that's much less rare, still occurs, but in general, it's a low NO3 issue mostly.
So rather than popping a pill to fix something, a band aid, I suggest a good cleaning, filter etc, CO2 twaking a bit, and good water changes + dosing.
This is not a disease, it's a symptom of a plant growth/care issue.
So treat it like that and you will have nicer plants, easier time doing the hobby, and few algae issus. There are many species of algae that canno be treated with a pill, then what?
Does anyone here claim to have gotten into this hobby to learn 101 ways to kill algae?
I've not met that person yet in 30+ years. Well, marine folks.........but none in th plant hobby.
So focus there.
You will have a lot more success.
Algae = something's up with my care routine and I need to look at adding enough nutrients consistently, check the CO2 real real good, etc.
Regards,
Tom Barr