If you want to take the hammer approach... A UV sterilizer should knock them out, or I have read that Ozone will do it also. I currently have a dino problem and just got an ozone reactor, so we shall see how it goes... but I also have a hair algae problem too, so I'm doing a completele blackout for several days in an attempt to kill off the hair algae (which is messing with my pH... which is causing my ORP to go way up... which is preventing me from running ozone).
Also, if you haven't already, I'd make sure you look at them under a microscope to make sure they are actually dinos.