Heya Joe,
If those polyps are opening a lot, then they're huuuungry.
Try feeding them some meaty stuff, rather than phytoplankton, since normally in the wild they eat bits of stuff drifting around, and zooplankton (the 'animal' type of plankton, not 'plant', like phyto).
My luck with Sun Polyps wasn't that great... I hope yours is better.
