Cool - I've made something similar before too - they work well. If your tank is new and you are not getting explosive growth, I wouldn't sweat it too much. Try feeding some at night, which might help - some corals actually "open" and extend feeding structures only at night. Favia's can be slow growers, zoanthids sometimes don't take food. Candycane, Duncans, other polyps should give a good feeding response - extending tentacles and capturing food. Reef Chili might also be too small for these - you might try something just a bit larger - bits of brine shrimp, mysis, etc. If you have a red light, you can wait for an hour after the tank goes to sleep, then target feed by red light without disturbing them too much.