pH Measurement

[Bradden]

Hi

I bought a pen type pH meter on ebay which drives me nuts as it's a pain to calibrate. I read that there are some with 2 calibration screws available ... but can find any. Where can I get a good quality meter that doesn't need calibrating every fortnight and is easy to set-up.
A couple of people have suggested using an Aquatronica or similar.. what I don't hear people talking about is calibrating them.. surely they drift as well?

[jobr]

I calibrate my PH probe on my Aquatronica every 12 weeks.

[Bradden]

Is it easy to do?

[jobr]

Very, pop it in to a glass of solution, wait a couple of minutes, press a button on the aquatronica, put probe in to another solution and bingo.

[kim]

If you want to CONTROL pH, an Aquatronica might be useful. But because it both measures pH and then controls (eg) pumps and valves accordingly, it's a bit expensive.

If you only want to measure pH, a simple much cheaper pH meter is all you need. Hanna Instruments do a good range - their site describes the relative accuracy and cost of the various models, but if you're determined you can probably choose from the site and buy much more cheaply on EBay.

www.hannainst.co.uk (http://www.hannainst.co.uk)

I use the HI 98128 version (accuracy 0.05 pH, 0.5 C temperature) and it takes seconds to calibrate (just stick in the fluid and press the button), plus spares such as probes are readily available.

There are cheaper versions if you don't want to go mad. But I like the fact that it doubles up as a pretty accurate thermometer.

kim