I think I had a old Rio pump (a VERY crappy pump) that pump water INTO my refuge from my sump. My refuge was higher than my sump so that the water simply spilled out of the refuge back into the sump. This is the ideal way to do it so that you don't have to have a pump inside your refuge. Impellers aren't good for the critters and such that will be calling your fuge home.
How are you planning on getting water to your refuge?
You are correct in that you don't need much water flow at all. Cheap pumps work great for this. You can always through in a couple of snails to deal with the algae that might grow in the fuge due to low water movement...