Just my two cents, but an observation from someone fairly new to the hobby. I've only been on the salt side for about 6 months now, but here is what i've noticed through the ups and downs of my tank. It is by no means "clean" yet as far as perfect water quality, yet my first lps, a duncan, grew two more heads in a month. My second piece, a frogspawn, i recently fragged as it started growing 5 more heads, two small ones are starting to come out of the main head as well. After these, i added an acan, some more zoas, some sps, two torches, and i had a leather in there i almost forgot to mention. About this time i had an issue with ich and after a few different trap attempts, i had to pull the tank apart to get the fish out into the quarantine tank. I put everything back together, removed the artificial decorations and added two more pieces of bleached rock. I also add phytoplankton to the tank a few times a week. I think after the change i had what was a planton bloom, i don't think it was bacterial as the water had a green tinge to it. i could see about 3 inches into the tank, but i let it handle itself. after about 2 weeks it cleared, my duncan growth caught me off guard. The leather grew about 1.5x its original size, the acan is sprouting 5 new heads, i got about a 1/4 or so growth on the green stag from two of its branches, and a few new zoa heads popped up, and the kenyan tree i had all but forgot about as it shed all its branches and looked like a ball, had about an inch of growth. Now i'm not saying cause a bloom, or do anything like what happened to me as i'm new, and it was a screwup on my part. my point of this is, and i hear it both ways, but you also read people are obsessed with zero water, i'm leaning towards the side of yes, keep the water decent, but a little dirt in there for them to feed i found better results with. just my opinion. Also, as for the base readings in my tank, dkh is 11.8, calc is 440, and mag is at 1360.
a zinnia is a flower, i think you're referring to xenia.
. ) but then 2 look like they are about to split, I can actually see one of the two starting to section off. and same with my frogspawn, it had one head that was splitting when i bought it, now one of the 2 heads is splitting, and it is the only lps coral I don't feed (well it doesn't like the food I feed.)