We might be confusing various strains of palys and zoas here. Most zoas won't take food suspended in the water column or brine ship and will close up. Larger species and most palythoa will happily gobble up brine shrimp and the like if you feed them with a turkey baster. Example of the later are purple deaths, nuclear greens, green implosions, etc. Green implosions will actually eat xenia if they get too close.
I've tried a lot of different feeding combos for dense and rapidly garden tanks and found the same formula seems to work. For most zoas rapid growth for me is achieved under nutrient / nitrate conditions that SPS won't like, although zoas / palys can be quite happy under ideal SPS conditions. If you want them to grow fast though, dirty water helps. I've tried a lot of different foods, and a thumbnail size chunk of beef heart run through a power blender and added once or twice a week seems to work the best. The added protein in the water which eventually breaks down into nitrate just puts everything into over drive. Direct feed palys that will take brine as much as they want.
Iodine drops (3 per week per 10 gallon) helps a bit, especially purple deaths keeping their color. I've also found the addition of kalk (added to the point of precipitation once a night) significantly helps deeper water varities like purple hornets thrive. Low / wide pH swings are what I theorize cause melting, and adding kalk at night reduces the available C02 that causes the low swing. Once I started kalk dosing any variety of zoa/paly I keep thrives.