The easiest way is to feed them directly mysis shrimp daily and do not keep them under direct, intense lighting. Take a half a cup of aquarium water, 2 cubes of mysis (in you have Fauna Marin UltraMinS add 2-3 drops), then let the cubes defrost. Once they have defrosted the mysis can be fed using a turkey baster. Turn off the pumps in the aquarium or put them on feed mode. If that option is not available to you, you can use 2 liter soda bottle, cut the top and make a dome over the colony to feed it. Another method is using a sterilized ceramic pot and doing the same. If the colony has does not have good polyp extension then the initial feeding of the colony will require more work.
Mike