When target feedin corals, there are several things that could derail your techniques. For one, hungry fish and invertebrates could swoop in at any time and simply take what your coral is trying to eat. The feeding response of corals is generally pretty slow, as they have to open and extend their polyps in order to move the food to their mouths. The other pesky problem is water flow. Target feeding your corals can be quite difficult if the water is blowing the food all over the place. Sure, the fish will probably be happy, but the coral will get very little. To solve both of these problems, you could build a little dome out of plastic. A tupperware container works great. Just drill a couple of holes in it, place it over the coral, and inject the food. Some inverts might be able to snatch up some food particles, but hungry fish won’t be able to get to it. This container idea is also a good solution for water flow, as it traps the food in close proximity to the coral allowing it to feed. But, if the flow still presents a problem, simply turn off the pumps.