Light and tubastrea - mine refused to open under 200W halogen lamps over kitchen counter, when I tried to feed it first time, in a separate container. After shading by newspaper - opened.
"Sweetwater zooplankton" should be daphnia, better to use saltwater origin food. The LFS should have the big refrigerator with the frozen cubes - mysis or ocean plankton (the last is bigger) should be good. $5 for 30 cubes - just thaw some in a saltwater.
The grocery food - just read the ingredients, no cooked, salted or with preservatives. Asian stores may have a lot of it. What I meant - do the search on reef food recipe, it will show you articles, like Adam Blundell's:
http://www.wetwebmedia.com/ca/cav1i3...ive_Recipe.htm , or farmerTodd's using the frozen food, scroll down to Feeding time:
http://www.farmertodd.com/presentation/default.htm , and Melev's Reef - feeding mysis to the sun coral:
http://www.melevsreef.com/pics/0604/suncoral.html .