wow that is a nice looking reef you have there!1. Most of my amphidinium stayed on the sand but it was in the rocks too in a lesser amount.
2. I removed sand weekly with water changes. I never removed all of it as I can’t get behind all the rocks. But 80-90% got removed.
3. I replaced a bit of the sand, maybe 10% or so. But stopped. The event was almost 4 years ago and haven’t added back any sand in 2 or 3 years.
4. I kept UV going for 6 months or so after dinos were gone. Then stopped that too.
I‘ll add my latest FTS
I just tried what the other person said about removing and washing the top layer then replacing it since I’m running a smaller tank (50 gallon lagoon) but if that doesn’t work after a few tries i might just pull the sand fully. I feel like diatoms and other algae will naturally take over if it moves into my rocks.
I did take some microscope samples as I was cleaning today and found very little dino in the sand that was left in the tank, and absolutely none in the sand I rinsed. We’ll see how this goes