I'm suppose to get a Bluelab pH pen tonight for $40 (open box / return). I'm wondering if I have to use BlueLab pH 4.0 & 7.0 calibration fluid or if I can use any brand. Thing I noticed is the Cal. Packets that come with the cheap pens say use deionized water to mix the solution. On the BlueLab box it says Do Not Use deionized or distilled water or it will ruin the pen.
The BlueLab 4.0, 7.0 pH solutions are $13 ea. for 250 ml. & the KCI storage solution is $15 for 100 ml. $41 + Tax just to Cal. a BlueLab seems pretty high considering the pH pen runs $120. For that price you should never have to calibrate.
Anyway, has anyone found a cheaper method ?
The BlueLab 4.0, 7.0 pH solutions are $13 ea. for 250 ml. & the KCI storage solution is $15 for 100 ml. $41 + Tax just to Cal. a BlueLab seems pretty high considering the pH pen runs $120. For that price you should never have to calibrate.
Anyway, has anyone found a cheaper method ?