I like my old classic version and hate the fact that you need to upgrade to the newer neptune to be able to use the trident. I love the kh guardian that I acquired from Lazy. After some upgraded parts and firmware changes it has worked like a charm. It only tests for alk but how often do we test for calcium and magnesium anyways. I am also able to make my own reagent for pennies so my operating costs are next to nothing. The waste water can be put right back into the tank and can also be monitored through neptune classic!! If you havent noticed I'm a cheerleader for the kh gaurdian rooting for the underdog:) Go team LOL
Jeff