I'm not a guru on Palys and Zoas, but I have had the time to experiment with different nutrient conditions with them in my frag tanks.
I have noticed that Palys seem to like the addition of meaty micro foods such as oyster feast, etc. Their skirts grow longer and they multiply a bit faster. I have not seen zoas respond at all to coral foods. I can't rule out phyto-plankton, but I'd be skeptical if it did much. Other LPS; acans, candy canes etc do respond to meaty micro foods being added.
In my frag tanks with no fish and hence no nitrate or added nutrients zoa and paly growth was almost 'zero', even with strong lighting over a period of six months. When I added a single small fish growth exploded.
White light LEDs caused Zoas to stretch towards the light. Turning on royal blue LEDs caused them to flatten out like they do under halides, which tells me they need far blue light. Which is rather obvious given they typically grow at deeper depths than many corals.
I've recently began experimenting with adding ammonia directly to one of my frag tanks with no fish for a couple reasons. First, to keep a nitrate cycle going, and second because I've seen some evidence that zoas thrive on ammonia given their affection for growing aroung sewer over-flows, etc. So far, they are growing just as fast with the artifical addition of ammonia as heavy stocked tanks, but I need a bit more time to confirm this. I also need to work out how much ammonia to use, etc. So far though, I might be on to something.
To sum up my own experience, paly and especially zoa growth respond far better to basic water nutrients like ammonia and nitrate (and fish poop which is a precursor to both) far more than adding micro foods. The later might likely decay into the former at some point, but it costs more.
