I really want to step in here... heres a link for a nice bulb which you should always run a reverse lighting cycle when you have a refugium and this light runs everytime your diplays off. You can use a biosediment like the one Kent sells. you want no less than 4 inches. Fill your refugium with your bio and fill it up with some water and a cup from your main display tank, or fresh saltwater, right before you fill the tank so when the water goes down the overflow into the refugium it doesnt disrupt the biosed to much this could really cloud the tank. If your refugium already has water in it add water to the biosed before adding it to the refugium. Maybe someone from your area has some nice Cheato to add in there. This will be a nive place for copods and other life to live a grow.
Light:
Melevsreef.com - Refugium Bulb
Biosediment:
Kent Marine Biosediment 6lb: Aquarium Supplies - Aqua Buys