just looked up some photos of dinoflagelates.. im pretty sure you're bang on. :-( is it manageable?

It's managable if you get on it ASAP. If you don't you'll have to go to durastic measures light no lights for several days... and your corals aren't going to like that.

Few tips:
-Use super pure water
-do a few big water changes
-reduce water agitation as it results in high dissolved O2 which the dino's thrive on
-Make sure your pH is spot on... they don't like highpH
-For some reason iodine doses kill them off a bit. No idea why, just an observation (do not overdose!!!!!)

ok so this may have come on at the worst possible time.. im going away for the weekend and have the tank in the hands of a fishsitter. im going to leave the lights off all day tomorrow, then go back to 4 hrs grow time for the weekend. first thing when i get back is a big water change and a clump of chaeto in the sump. just ordered a TDS meter to see how my RO filters are doing and i might be purchasing a new unit... put an add up looking for media reactors for carbon or GFO. thoughts on my action plan?