I just got my Merlin (I think it is a Red Sea product) running on my freshwater tank after sitting in my garage for the past 8 years. It is actually quite easy to get going, just hook it to a pump (I use my return pump) and slowly open the built-in valve until the sand fluidizes and reaches a level marked on the side of the clear housing.
As to whether or not it works...
It sure looks neat!