Feeding corals comes at the expense of water quality: the more you feed, the lower your water quality will get. Feeding corals will increase their growth, but the increased phosphates in the water can slow or stop growth altogether, so there's a careful balance that needs to be maintained.
Most reef keepers feed their corals frozen mysid or other frozen meaty foods, ranging in size from krill (larger) to cyclop-eeze (tiny). The main problem associated with feeding frozen foods is that the liquid from the food will leach nutrients into the tank. Any defrosted frozen food will contain a fair amount of water that is loaded with nutrients that love to lower your water quality. Some hobbyists even "clean" their frozen foods by washing them with a small amount of tank water before feeding, which will remove some of the excess water. Unfortunately, since the frozen foods are fully hydrated when frozen, they will leak a fair amount of nutrients into your water column, whether cleaned or not. Herein lies the magic of pellet food.
First of all, not all pellet foods are created equal. Some are complete garbage, and others are phosphate factories that provide no real nutrition to your corals, especially being that most pellet foods are meant for fish, and not for corals. Two foods that I have had excellent results with in the past are Hikari's Marine S and Marine A pellet foods. I currently use Fauna Marin's LPS pellets which are fantastic but pretty large, so you only need to feed one per LPS polyp.
hese have been like a miracle food in my farm, giving explosive growth on nearly all of my LPS. Marine S is a smaller pellet food, well suited for smaller polyped LPS such as Favites and Micromussas. Marine A is a larger pellet food, and does amazingly well with larger polyped corals such as Acanthastrea lordhowensis and most Favias. Dendrophyllias respond to Marine A with massive growth over a short period of time. Either of these pellet foods works very well on sick corals that are not doing very well, or on newly fragged corals that need large amounts of nutrients in a very short amount of time.
The inherent advantage of pellet foods is two-fold, the first being that they do not leach nutrient-laden moisture into your tank, they actually are hydrated by the water in your tank, and as a result keep their surrounding water very clean. The second advantage is that there will be no leftover food that can't be cleaned. Since you will be feeding your tank with all of the pumps turned off, each coral will need to be fed manually, and any food that does not make it onto the coral will drop onto your sand bed. This leftover food can be picked up and removed after the corals are done feeding, so that absolutely no excess nutrients are leached into your tank!
Pellet food also contains substantially more nutrients per unit than any frozen food, so feeding with pellet foods is like a double or triple normal feeding, and your corals will respond with double or triple growth. This is one of the main secrets (not anymore) to having a farm system that is brimming with corals that are ready for trading!