Quote Originally Posted by Ocotillo
It sounds sort of funny, what is "manual tester"? Aquarium fish tank drops? Do you mean one of those probes with the needle that move? Those are tricky because they are "open to interpretation" and take some getting to know. Others call them just plain inaccurate. I don't use them anymore, a digital like the Milwaukee are decent IMHO. Fish tank drops are pretty accurate but water color must me "compensated" for which leads to, again, interpretation. Perhaps others will correct me if I'm wrong please.
Thanks, Doc Oc.

the drops mate thats what im using