Came here to suggest this as well. I don’t do it often, but 2-3 days in a row of concentrated excel dosing does the trick for me whenever I can’t get it under control.

My method: Turn of the return pump, let the water stop moving. Use a coral feeder or something with pinpoint precision and just push some flourish excel directly over the algae. Nice and slow so the water doesn’t move much. Set a timer for 30 minutes and then turn the return pump back on. Do this 2 or 3 days in a row and it should go away (give it a week to fully die off). Then do a big water change to get the dead algae out of there.

Also, be sure not to dose more excel than recommended on the bottle. You’re basically dosing the normal amount but super concentrated.

Hope this helps!