Ronald

i dont know of any Tds that can measure percentages either, i was just reading off the label and kents info about the 40% of my tds readings being KH, and thats what i go by.

The dripper test kits are perfect for finding out what GH/KH you have in your tap water, but for me using RO right its useless. and it definatly varies all over the place from city to city.

all depends on what you start with, like you said, some tap water will have high tds but itll all be GH and be totally unstable. others will be all KH with no GH and have rock solid ph.

measure it, find out what you got, then adjust it, only if you need to

Thanks Ronald