It is not conflicting with what @ScottB said. It has affect against some strains can be forced to water column. Even works somewhat with small cell Amphidinium but the process is slow based on the few hundred posts I have gone trough and based on my own fight.I believe I have Prorocentrum. I've posted a picture and video above. I also sent a picture to taricha who was leaning that way as well and suggested UV.
I am firm believer is the aim is not to kill Dinos but help the competition to do the job for you for long term success.