I need to dilute a concentrate 3:1 with water. Does checking PPM with a meter give me any indication of mix "quality" if the concentrate has 7 different chemicals in it? One of the chemicals is a salt.
Any "dilution" of an homogeneous solution will result in equal proportions of all of the compounds. Checking any of them for accuracy or confirmation will result in the same relative change value for all of them. With multiple components the only concern would be that whichever one you use for the test is not interfered by any of the other compounds.