I don't think it is a parameter issue, though I think the phosphates and nitrates are too high for any system with SPS
in it. Stylophora coral, your cats paw, is a more moderate light SPS
, so a 4 bulb should be enough light for it if it is in the upper half of the tank. Get the phosphates and nitrates down and the polyps will come back out. If I make a mistake in my tank and these levels rise, the polyps on my SPS
retract as well.
In terms of your xenia, in all honesty sometimes they do great in systems and other times they just won't grow. Normally, I point to alkalinity for the decline of soft coral such as this, but with it being just above 9 if my calculation is right there it is fine and the calcium is higher than average...but this shouldn't effect a soft coral as such. I'd point to the phosphate and nitrates again.
A general rule of thumb for reef tanks is to keep these as close to 0 as possible. 20 is doable for nitrate, but aim for 0. Same with phosphate.