eyup all,
i've not calibrated my ph pen for a while cos i ran out of calibration fluid (ph4 and ph7) and noticed i was getting unrealistic readings from my pen so i bought some calibration fluid...
trouble is, i've forgot how to do it.
do i use the ph4 fluid first then the ph7 fluid or the other way round???
i seem to remember that was what instructions directed but...i am a stoner...

any-one know for sure?

ta all:-)
ydl

Reading from the leaflet....remove cap and rinse with water,shake tester with a snap motion..dip sensor in buffer solution for caliberation..hope it helped it dont mention buffer 4 only 7...

i think i'll clean proba and dunk it in ph4 fluid then clean it again then dunk it into ph7 fluid (and calibrate ph pen each time to corresponding fluid...)
sounds like a plan...