Dinoflagellates

[Delphinus]

Siphoning didn't work for me. It would just come back 100% within a matter of hours. I noticed, however, that it would all but disappear at night and be almost 100% gone by morning, so I finally gave up and left my lights off for as long as I could bear to have my reef without lights. My original goal was a week without lights, I lasted nowhere near as long. I think I went for 2 or 3 days of complete lights-out, then just left my actinics on after that but no halides whatsoever for the remainder of the week. After the week without halides the dinos were gone.

After a week without halides though, I was very nervous about turning them back on and causing UV damage to the inhabitants so I did the 1/2 hour on / 1/2 hour off thing for the next week (normal photoperiod otherwise), then 45 mins. on / 15 mins off for the next week, then finally back up to normal.

Good luck. Dinos are an absolute nightmare, anyone who's had them will surely agree. They're horrible. At many points I was about to admit defeat and sell the tank, it was unbearable to look at. So fear not, we feel your pain! Good luck.