A very tempting pH meter. But...

[Jees]

In search for a nice pH pen, I stumbled on (ebay) this very price attractive Chinese gadget:
23.5 dollars :want:

A highly accurate pH meter with 2-liner display. It simultaneously measure and display pH level and temperature. Featuring its Waterproof design and temperature units can be displayed either in °C or in °F. In addition, high sensitivity, fast response, and good repetition detachable pH electrode can easily be replaced anytime. Just immersed the meter half pass the tip of the sensor or up to the middle of the body from the sensor tip.

Temperature plays a very important role to ensure 100% accuracy in reading results. With built-in ATC pH value is automatically adjusted in temperature between 0~50°C (or 32~122°F) so you don't need to worry about the effect of temperature change on pH level. A very useful pH meter to test pH level of liquids in various industries and applications such as Hydroponics, Aquariums, Swimming Pools, Spas and Food processing etc.

Special Features

Large LCD screen with dual display : pH and Temperature (°C or °F)
Replaceable pH Electrode (just add US $9.80 / GBP £5.90 / AU $11.90 / EUR €6,90 for extra electrode)
Built with Automatic Temperature Compensation (ATC)
Switchable °C and °F
Easy to use with high accuracy
Waterproof design that can withstand wet environment
Compact and light weight for mobility
Batteries and Calibration Solution (pH 4.003 & pH 6.864) included
Guaranteed high quality and accurate testing results

Specifications

pH
Measuring Range : 0.00 - 14.00 pH
Resolution : 0.01 pH
Accuracy : ±0.1 pH
Temperature
Measuring Range : 0~55 °C & 0~131 °F
Resolution : 0.1 (°C / °F)
Accuracy : ±1 (°C / °F)
Automatic Temperature Compensation (ATC) : 0~50°C (32~122°F)
Operating Temperature : 0~50°C (32~122°F)
Batteries : 4 x 1.5V AG13 Button cell Batteries (included)
Size : approx. 188 x 35 x 35mm
Weight: approx. 98g

Standard Set Includes:

1 x pH & Temperature Meter
Set of pH 4.003 and pH 6.864 Calibration Solutions (FREE)
4 x 1.5V Button cell Batteries
1 x Mini-Screw Driver
1 x Instruction Manual
Standard factory package
OPTIONAL: Just add US $9.80 / GBP £5.90 / AU $11.90 / EUR €6,90 for extra Replaceable pH Electrode

This looks all nice but there are a few things that are not explained and need attention:

* Automatic Temperature Compensation: this is measured ambient, not in the sample! So one must let sample come to ambient temp to be correct.

* Calibration: it comes with 2 little calibration pots, so one would think there is 2 point calibration, what else to expect from a 0.01 display meter. Wrong, it is only one point calibration.

Nevertheless, for that price not bad, but just in case you want to buy, better know the ins and outs. That "Guaranteed high quality and accurate testing results" is just advertising, your stuck with +/- 0.1 pH error on a 0.01 resolution display. I don't know about other pen's but this one drift easily.

 

[Orion]

For that small error margin if nothing else this is actually quite a good price. Generally these chinese kinds have the same innards as a more expensive branded original (as I'm sure half the forum has probably experienced with those milligram scales).

The next best modestly priced (cheapo) pH meter is half the price but super unreliable, as in give you a different pH by 2 points a few minutes later from the same sample spec.

 

[MachineElf88]

I have that exact one. Works great.