I too have considered a system similar to this but am starting to reconsider due to the skepticizm appearent. Please take a look at the following link for a similar system but utilizes ultra violet light instead of sound. The unit's craftmanship and materials appears to be very high quality.
http://www.ultraviolet.com/water/ecolog01.htm I don't mean to change focus on Heybud's inquiry but thought that this could be a viable alternative if its effectiveness could be confirmed and the price is managable. Does anybody have any experience with this system? Or is this another 6 one way, half dozen another?