Is your water clean? Zoas does not like crystal clear water. Mag 1330 is fine. The purpose of Mag is keep the balance of the CAL and ALK so it won't affect the grow.
I just read about the Mag week ago but cannot find the article any more.
I have great growth with no coral feeding. I've talked to a few serious ZOA keepers and they agree not to feed zoas. Palys might eat but zoas usually don't. The excess food eventually will build up between polyps and can cause sickness to the colony. I'd be willing to bet its not food that ignited your growth, but simply the polyp settled in. I've noticed for the best growth don't touch your polyps. Find a spot they are happy and let them grow. I have polyps that are notorious slow growers that grow like weeds for me. My best growing zoas are those I glued months ago and didn't touch.
Yes, now that my bubble situation is gone, my water is crystal clear. I'm a freak about keeping my tank clean, and I do 25% water changes once a week. I know I'm doing something wrong, just don't know what.
With a 29g tank, I change 5g a week, giving that it prob only holds 25-27. Is that too much?