I really could be happier with my zoanthids. A lot of them aren't always open and I suspect:
1. Flow - hopefully I'll install a better wavemaker soon and that will help them out
2. Low nitrates - my goal for years, and now its too far, I'll likely bring a clump of my evergrowing cheato to the LFS to give them for free or just give it to anyone there who wants it
3. I don't dose - I don't think I should have to, but maybe?
4. Water changes - I do these more to put minerals back into the water, obviously nitrates aren't the problem
One thing for sure, my filter is working well. Still zero nitrates and phosphates (phosphates is cool because I don't run a skimmer, ever, little trick I learned from my old LFS: remove skimmer, double down on biomedia, and add seagel)