I have never had a problem with the PHs when feeding my damsels. They, like clowns, seem to enjoy the chasing of the food through the current. I usually feed mine frozen mysis, frozen cyclops and flake. They love the mysis and cyclops. They swim all around like crazy trying to get the little cyclops.
If you are worried about having the hermit crab in a reef thank then I would suggest maybe a shrimp like a peppermint. My peppermint shrimp absolutley goes nuts over any frozen food and believe me, he will pick up any left over piece of food the falls below, be it flake or frozen. He is a goofball.