Hanna Checker pH Tester

[@FALAHAL-KAABI]

Dear If I do this procedure but I do not get the suitable value (4.01 or 10.01) can you explain why?

[@wisamism3373]

ihave that ph checker but its digits not stable. it keeps chnging values when put the probe in any solution... any help

[@timothygrady7552]

Same here. I use probes all day and this drifts no matter what.