Is this legit? What good would it do for your aquarium? What good is it claiming to do?
http://www.ecoaqualizer.com/aquarium_filter/technology.php
http://www.ecoaqualizer.com/aquarium_filter/technology.php
http://www.rexgrigg.com/debunked.htm
http://www.saltcorner.com/Reviews/showreview.php?reviewID=19
Big fat load of hokum if you ask me. Can't find the link at the moment, but a few years ago, someone actually took one of them apart, and found that basically it's just a drinking straw with a few magnets stuck to it with electrical tape inside a pvc casing. In any case, actual effectiveness notwithstanding, I don't see why something like the eco-aqualizer couldn't be easily diy'ed for a fraction of the cost. In the interest of fairness I'm posting an argument for and against, both written by well respected names in the hobby. Having never used one I can't say for sure that its a scam, but that's definitely what I'm leaning towards.
And if you connect it inline in the fuel system of your car you'll get 200 mpg!