briansone

Hi All, I am in the market for a colorimeter to test pool water accurately & reliably. I have been searching equipment sites & am overwhelmed with the choices & price points. I don't want to break the bank, I don't think I need to, it's just colorimetry, right? So I'm hoping some educated opinions can keep me on the right track & away from a bad value decision. I need to test: - pH - alkalinity - calcium/hardness - cyanuric acid - free chlorine Questions I need answered are: - why do most colorimeters claim they test only for a subset of the above? Isn't it just a case of adding more concentration charts? - anything wrong with buying a 2nd hand colorimeter? - what are some of the more reputable lab equipment sites to look at? - what would you buy considering the goals above? Thanks in advance, Brian.