For what we are doing most of the time (as orchid growers) the pH paper
is probably sufficient. You can buy a good quality paper, if you want,
which is often marked in rather small increments. You can get different
ranges, but for orchid use something calibrated between pH 4 and pH8 is
sufficient. Spend a little extra, and get the high quality stuff.
This is probably good enough even for home flasking and other solution
making. Now, if you are doing serious scientific endeavours, then by
all means get yourself a real pH meter and learn how to use it properly.
Some things require exact measurements. But, frankly, for fertilizer
solutions and flasking media, you just have to be close. And in my
experience you don't even have to be all that close. pH paper is good
enough, and it is a heck of a lot easier to use.
Of course if you are using highly colored solutions, then all bets are
off... Hard to see the pH marking paper in a beaker of charcoal
solution.... This is where a meter comes in handy.
Rob
I'm a biochemist, and in my experience even in a laboratory
environment it requires quite a bit of care to keep a pH electrode
working properly. They are fragile and sensitive to contamination
with organic materials. What I try to do is make my solutions up by
weighing
out the buffering acid or base and its salt so I know what pH I'm
getting, rather than the traditional HCl titration. Then you can
check for crass errors with a pH paper if you want to. This makes
for more consistent buffers. I wonder if a similar aproach could
work for nutrient solutions for orchid culture. Phosphate would be
the obvious buffer salt but you'd probably need 10 millimolar which
if my mental aritmetic serves is 310 ppm of P, perhaps higher than
you'd want. I wonder if organic buffer salts such as tris have been
tested for this purpose?
--
Rob's Rules:
http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit