I haven't tried vitamin C dosing, other than a bit in the food for lateral line disease, but this thread is pretty thorough.
http://reefcentral.com/forums/showthread.php?t=1602494
I'm surprised your nitrate and phosphate is zero and your calcium is 400 and alk 8, considering you have so many stony corals and you don't use carbon, phosphate remover, algae or coral harvesting, much in the way of a sand bed, ozone or UV sterilization. You also seem to have modest feeding practices (no phyto, baby brine, or rotifers). Usually coraline algae is a probiotic way of outcompeting nuisance algae, but you have stated that you discourage its growth. You don't have a calcium reactor or a balling system, not even a two-part system. Maybe it's a lot easier to maintain calcium with no coraline algae to compete against.
Your old tank looked like it had the works, and the new one is pretty minimalist. What do you attribute your success to?