My Zoa's looked very similar to yours until recently where I started dosing a selection of things from the Coral Essentials range, along with phytoplankton. Iv'e also started regular feeds of reef roids. The zoas, and all my corals have turned around in the space of a couple of weeks and are now looking great. I was scratching my head too as the main parameters were fine. I just wasn't feeding them. Calcium and magnesium are same as you. Alkalinity is at 11. It's been sitting there for a week now, hoping it will slowly reduce. NItrates 10, Phosphates 0.09. Hardly doing any water changes now, under 1% / week. I would consider saving up to get a Hanna UL phosphate checker.