PH Meter Question ... do they work in freshwater?

[JBendel]

This may belong in the Lounge

Anyone know if the Pinpoint American PH Monitor's work in fresh water?

The wife was going to borrow mine for a science experiment with some 4th graders and when I dipped the probe in some distilled water ... it registered 9.0 .... swirl the probe around and the PH drops, but all reading are very unstable .... I recalibrated it ... no real difference, but when it's back in the tank ... it's stable and reading as expected.

I lost the meter directions long ago, but I suspect the probe only works in salt water... anyone know for sure?

 

[NateHanson]

I think they work in either, but very pure water doesn't have any buffering capacity, so measuring the pH of RODI or distilled water is meaningless. Try putting a sprinkle of baking soda in the water, and then measure the pH. It should be more consistant. Or measure your tap water.

 

[Fitzy]

Agreed..... pH is pH. It doesnt matter what you use the probe in. For example, in HS, did you use different litmas (sp) papers for each type of liquid??

My dad actually had a pool test kit that he use to use back in the day. It would test pH, Clorine (sp) (He used Tap water), and Alk.

 

[JBendel]

Thanks all for the help.... used the baking soda, but ended up using a Tetra Test kit, since the color difference gave better contrast than an absolute number off a meter.

For what it is worth .. kids were blowing bubbles in water glasses before and after exercising and using PH as an indicator to how much CO2 they were exhaling.