Hello, I currently have a 55gallon fish tank. I have a MegaFlow Model 2 Sump. Picture below. This is hooked up to a overflow box on the back of my fish tank. I want to put a refugium into my cycle. Now I would like suggestions on where to put the inlet line. I was thinking about taking the water right form the overflow box into the refugium. Then returning it to the return part of the sump. However, im not sure what to do, thats why im here

Any suggestions would be great. Also what should I keep in the refugium? I have read about Caulerpa and Amphipods. I also think I should use about 3inch bed of sand. Anything else or what should i put in there? Thanks very much