AF does not work on bryopsis or other siphoning algae. Siphoning algae heal their exterior cell walls to quickly for AF to work. AF makes holes in the outer cell wall causing the contents to spill out and also enters the cell causing damage inside.
If you look at a siphonous algae under a microscope you can see that the algae has extremely large cells which can actually branch out. So their cells are very large. When a siphonous algae is broken the cells heal themselves very quickly.
Siphonous algae cell
MORPHOLOGICAL DIVERSITY
WITHIN THE ALGAE
http://scitec.uwichill.edu.bb/bcs/bl14apl/algae2.htm