@dwest Im right there with pulling the sand, thats the plan this weekend. Curious, did you do anything besides UV when you went BB, and did the dino go pretty fast once you pulled the sand?Sorry you are dealing with these.
I had amphidinium a couple years ago. I fought them for quite a while and incurred quite a bit of loss along the way. I finally made huge progress after I removed my sand bed, while continuing in-tank UV.
I always thought I would put my sand bed back in. But 2 years later I still have a bare bottom tank. Good luck to you.
Thanks