Sciencemadness Discussion Board

Question About Cheap Digital pH Meters

jpsmith123 - 13-11-2005 at 18:07

Does anyone know how well the cheap ebay variety of digital pH meters work for testing chlorate and perchlorate solutions? Thanks.

Regards,
Joe

DrP - 21-11-2005 at 08:53

I was given some cheap plastic pH meters. First I was pleased the freebies, however, I found I had to re-calibrate them before nearly every reading. I'd calibrate, get a reading and then 5 mins later the things had drifted way off.

I have heard good report about some cheap meters being stable, but not in my experience, so i think it would be pot luck. We paid about £140.00 for ours at work a couple of years ago and it is still really solid. (needs re-calibrating every year or so).

I guess it depends on your requirements - if it is going to get industrial levels of use and the results are for quality controll or something where you really do not want a spurious reading, then get a decent one. If you only want to test occassionally then you might be ok with a cheapie. Suck it and see.

lordmagnus - 16-1-2006 at 23:53

I bought a HANNA instruments CHECKER model, it works well for my lab, and my aquarium. After about a dozen test over a two day period,I rinsed the tip with distilled water, shook dry, and placed in the 7.01 PH buffer solution, and it had drifted more alkaline, so I adj. the 7.0 set screw on top, back till it gave a steady read of 7.01-7.02 and all is well again, for the $30 I payed, it is a great little instrument. I also use it to check the life remaining in my citric acid stop bath for my black and white photography.

dedalus - 24-6-2007 at 12:43

Quote:
Originally posted by lordmagnus
I bought a HANNA instruments CHECKER model, it works well for my lab, and my aquarium. After about a dozen test over a two day period,I rinsed the tip with distilled water, shook dry, and placed in the 7.01 PH buffer solution, and it had drifted more alkaline, so I adj. the 7.0 set screw on top, back till it gave a steady read of 7.01-7.02 and all is well again, for the $30 I payed, it is a great little instrument. I also use it to check the life remaining in my citric acid stop bath for my black and white photography.


Enthusiastic second!

That Checkr is one of the best values around.