Carl 1 Lucky Texan wrote:

http://www.ph-meter.info

Although the site is somewhat user hostile,

Care to drop me a line and explain why do you think so?

strips and pH papers/indicators. Plus, I see no reason a 'pen' or probe
type device couldn't be used in a soil slurry or other very wet, soil
derived solutions.

There is one problem - glass electrode (or more precisely the bubble at
the end) is made of extremally thin glass, thus it is very fragile. But
that's not a problem you can't overcome with good engineering. Note,
that due to the way pH electrodes are made they will age - at best they
can be used for about a year (gell type). Flowing electrodes can be
used much longer, but they are difficult to maintain.

And it IS likely, especially given the difficulty of
soil testing as provided in the other ratehr good link, that decimal
point accuracy means little - but if it comes along with an inexpensive,
convenient, long shelf life piece of test equipment, I see no problem
with that.

See my other reply - one decimal digit is important. I wonder if the
difference between 6.5 and 7.5 won't be large enough for the hydrangea
to change flower color.

Some folks may find a way to use a pen or probe for multiple
duty - soil, tropical fish, pond, etc.

Yes - and soil electrode (while best for soil pH measurements) can be
used for such applications as well. But it will be probably overkill,
IMHO pH stripes will do in all these cases.

Mr. pH