i'm in the process of converting my wet/dry into a refugium. thing i've learned so far is not to put a whole lot of over-thought into it. i simply dammed up the buttom where the water flowed previously, drilled 6 - 1/2" holes about 8 inches above (make sure to pull the power to see how much water flows in from you overflow box so you know how high it has to be if the power goes out and you don't want a flood) th bottom of the tank. i kept my return sump as is. i am really just doing this now, just this morning i started adding some live rock rubble, and tomorrow i'll be adding the light. so far, so good. i don't know it his is right, and nobody on this site offered any help, so i winged it and am hoping for the best.