i dont believe the area in side of one of those would be sufficient, depending on the size of your tank of course. i ahve a couple of extra wisper 5 laying around from the fresh water days (ahh the good ol'days when things were simple) and they are deep enough but not wide enough.
Whit, people have done this with some of the larger aquaclear filters. It is doable but the flow may be too high if you want to put sand in there. Look on nano-reef.com there are several threads about people using aquaclears as mini - refugiums. On a larger tank they are really not going to do much good but any additional biological filtration can't hurt IMO.
