You can spot feed right in the tank...they like a little bit of reflected light...not complete darkness. If you are going to be putting the coral on the sand bed, a small plastic water bottle with the bottom cut out will allow you to put the bottle over the coral and drop in food the top. Truthfully a 3 gallon tank is so small that any food put in should be kept in circulation by flow and allow the coral to feed. Just turn off the skimmer (if you have one) for a little while to allow the food to remain in suspension. Or you can just spot feed with a pipette....baby brine, cyclopeeze, small food. Thaw food in tank water and using the pipette or eye dropper, take out some of the water (not food) and puff it at the sun coral. Kind of like priming the pump..it will make the coral realize there is food coming. Give it a few minutes to extend, then gently puff some food into each polyp...easy enough. Removing the sun coral to feed it will stress it out far more than just letting it catch it's own food in the tank.
My sun coral (a black and green one) was glued to the face of a slight overhang. I do not feed it directly, but it has doubled from 3 polyps to 6 since early February when I got it. I feed Rod's food and DT's phyloplankton after lights off and turn off the skimmer until morning. It's on a timer. That way there is food in suspension in my tank all night long....every chalice I own begins extending it's feeding tentacles after lights out...you can see them actively feeding. All my coral, acros, zoas, have begun feeding more actively since I began doing this, colors are better as is the growth rate.
