Hydroponics stores tend to be boutiques with boutique prices. As I got into
this hydroponics, I wanted to buy a pH meter. It is getting more and more
difficult to get lab equipment and chemicals. As I got into this
hydroponics, I wanted to buy a pH meter. I selected a Corning ChekMite
because I thought I could rely on the Corning cachet. I found that VWR
claimed that it was a restricted device. Presumably it was that because of
the war on drugs. I finally got it from a scientific supply house.

This same house, however, will not sell me chemicals, primarily because of
liability. Many such places will sell only to businesses and not to
individuals. One of the last places around the LA area where individuals
could get supplies, TriEss sciences went out of business when the owner
died. When I was there, there was a notice that iodine crystals could not be
bought with out some kind of a permit. Again, I think because of the
misguided war on drugs.

I have been getting hydroponic nutrients at reasonable rather than the
boutique rate3s that pot growers are willing to pay. I get formulations of
all the nutrients in granular form. A few years ago, after Oklahoma City, I
was at a fertilizer place where they still were selling bags of ammonium
nitrate and potassium nitrate. I don't know how available these substances
are are now. I am content to get the mixtures.

Well, I still do not have a good pH test method. The glass electrodes in pH
meters tend to last only about a year and are expensive to repair. Using
indicator solutions is awkward. I think that I am going to end up using some
of the test strips.

Bill
-- Fermez le Bush--about two years to go.

You can also try to get color indicating titration kits. They are
simple to use. They have a graduated flask to hold the sample and you
count the drops to color change to get a pH or other wet chemical
concentration like Chlorides or Nitrates. I have used these in
manufacturing plant situations where operators need pH or cleaning
chemical concentrations to do their job. No real lab skills or
expensive to repair equipment needed.

If still want a digital pH meter you can get calibration solutions and
do the servicing yourself. You should also be keeping a glass probe in
deionized water when not in use. There are also polymer membrane
probes you may want to look into instead of glass. If you know that
you are always basic or acidic you could also opt for a generally more
rugged conductivity probe and convert the number you get to pH.

Jim


On Jan 23, 6:11 pm, Salmon Egg wrote:
Hydroponics stores tend to be boutiques with boutique prices. As I got into
this hydroponics, I wanted to buy a pH meter. It is getting more and more
difficult to get lab equipment and chemicals. As I got into this
hydroponics, I wanted to buy a pH meter. I selected a Corning ChekMite
because I thought I could rely on the Corning cachet. I found that VWR
claimed that it was a restricted device. Presumably it was that because of
the war on drugs. I finally got it from a scientific supply house.

This same house, however, will not sell me chemicals, primarily because of
liability. Many such places will sell only to businesses and not to
individuals. One of the last places around the LA area where individuals
could get supplies, TriEss sciences went out of business when the owner
died. When I was there, there was a notice that iodine crystals could not be
bought with out some kind of a permit. Again, I think because of the
misguided war on drugs.

I have been getting hydroponic nutrients at reasonable rather than the
boutique rate3s that pot growers are willing to pay. I get formulations of
all the nutrients in granular form. A few years ago, after Oklahoma City, I
was at a fertilizer place where they still were selling bags of ammonium
nitrate and potassium nitrate. I don't know how available these substances
are are now. I am content to get the mixtures.

Well, I still do not have a good pH test method. The glass electrodes in pH
meters tend to last only about a year and are expensive to repair. Using
indicator solutions is awkward. I think that I am going to end up using some
of the test strips.

Bill
-- Fermez le Bush--about two years to go.

On 1/26/07 5:49 AM, in article
, "
wrote:

ou can also try to get color indicating titration kits. They are
simple to use. They have a graduated flask to hold the sample and you
count the drops to color change to get a pH or other wet chemical
concentration like Chlorides or Nitrates. I have used these in
manufacturing plant situations where operators need pH or cleaning
chemical concentrations to do their job. No real lab skills or
expensive to repair equipment needed.

If still want a digital pH meter you can get calibration solutions and
do the servicing yourself. You should also be keeping a glass probe in
deionized water when not in use. There are also polymer membrane
probes you may want to look into instead of glass. If you know that
you are always basic or acidic you could also opt for a generally more
rugged conductivity probe and convert the number you get to pH.

Thank you for the information. I do have an indicator solution that will
work although the pH meter is more convenient.

I have been storing the electrode in a pH7 buffered calibration solution.
Would it help if I store it in a concentrated KCl solution? That seems to be
the way the electrodes get shipped. Where can I get information on how
electrodes fail?

Bill

On Jan 26, 2:49 pm, wrote:

If still want a digitalpHmeteryou can get calibration solutions and
do the servicing yourself. You should also be keeping a glass probe in
deionized water when not in use.

http://www.ph-meter.info/pH-electrode-storing

Don't store electrodes in DI or RO water - unless you want to damage
them irreversibly. You may store electrode in DI/RO water for a short
period of time - few hours at most - when doing a series of
measurements. When stored for days or weeks keep it either in the
solution provided by the electrode producer, or in the pH 7.00
calibration buffer - or in the KCl solution.

Borek
--
http://www.chembuddy.com/?left=BATE&right=pH-calculator
http://www.ph-meter.info/pH-electrode
http://www.bpp.com.pl/?left=dysleksja&right=dysleksja
http://www.terapia-kregoslupa.waw.pl

On Jan 26, 7:46 pm, Salmon Egg wrote:

I have been storing the electrode in a pH7 buffered calibration solution.
Would it help if I store it in a concentrated KCl solution? That seems to be
the way the electrodes get shipped.

See my previous post. In general both pH 7.00 buffer and KCl solution
should do the trick. However, you should check users manual - sometimes
one solution is preferred over the other. n most cases it means
producer tested the elctrodes in one of the solutions and is sure
electrode will work correctly if stored this way. This doesn't
necesarilly mean that the other solution won't work.

Where can I get information on how electrodes fail?

You mean how to find out if the electrode fails? If you can't calibrate
pH meter, if the indications are fluctuating you know something is
wrong. As long as you have no problems with calibration electrode is
almost for sure OK. You may move electrode several times between
buffers to see if it keeps displaying correct value, just don't forget
to flush the glass each time with DI/RO water before dipping (to
prevent buffer contamination, dilution shouldn't change pH,
contamination can).

Borek
--
http://www.chembuddy.com/?left=BATE&right=pH-calculator
http://www.ph-meter.info/pH-electrode
http://www.bpp.com.pl/?left=dysleksja&right=dysleksja
http://www.terapia-kregoslupa.waw.pl

Sorry. Brain fart. Glass electrodes should be stored in the pH4 KCL
buffer solution. To recondition a probe, soak it overnight in pH 4
buffer containing an additional 10 g of KCl for every 100 mL.

In food plants no glass, so the lab is already using ISFET pH
electrodes(solid state). We either store them dry for the portables,
or in D.I. water for the table top units that are used 3 shifts/day.

In article .com,
wrote:

On Jan 26, 7:46 pm, Salmon Egg wrote:

I have been storing the electrode in a pH7 buffered calibration solution.
Would it help if I store it in a concentrated KCl solution? That seems to be
the way the electrodes get shipped.

See my previous post. In general both pH 7.00 buffer and KCl solution
should do the trick. However, you should check users manual - sometimes
one solution is preferred over the other. n most cases it means
producer tested the elctrodes in one of the solutions and is sure
electrode will work correctly if stored this way. This doesn't
necesarilly mean that the other solution won't work.

Where can I get information on how electrodes fail?

You mean how to find out if the electrode fails? If you can't calibrate
pH meter, if the indications are fluctuating you know something is
wrong. As long as you have no problems with calibration electrode is
almost for sure OK. You may move electrode several times between
buffers to see if it keeps displaying correct value, just don't forget
to flush the glass each time with DI/RO water before dipping (to
prevent buffer contamination, dilution shouldn't change pH,
contamination can).

Borek
--
http://www.chembuddy.com/?left=BATE&right=pH-calculator
http://www.ph-meter.info/pH-electrode
http://www.bpp.com.pl/?left=dysleksja&right=dysleksja
http://www.terapia-kregoslupa.waw.pl

Old Alligator-Mouth here again.

My experience has been that the glass probe should be kept in a pH7
buffered soaking solution (ask supplier). You may want to get some
"Parafilm"tm as well, so that you can seal the beaker (typically 50 ml),
the probe, and soaking solution from air-born contaminants. You will
also need some pH7 and pH4 calibration solutions (typically yellow and
red, respectively).When you calibrate the pH meter (see manual) you will
want a slope somewhere between 98 and 102.Finally, you'll need electrode
solution to top-off the pH probe or to refill it when you can't get the
slope into the desired range. Like most jobs, set-up and clean-up are a
significant part of the work.

You may want to have a temperature probe as well because the probe is
temperature dependent and the readings will have to be adjusted if
significantly above or below 20C (68F).

Bonne chance,

- Bill
Coloribus gustibus non disputatum

On Sun, 28 Jan 2007 22:37:12 +0100, William Rose wrote:

want a slope somewhere between 98 and 102.Finally, you'll need electrode
solution to top-off the pH probe or to refill it when you can't get the
slope into the desired range.

Depends on the electrode type - most electrodes sold now (especially to
end users outside chemical/research community) have gelled electrolyte
which can't be replaced, thus electrode after serving for 6-9 months (12
at most) have to be thrown away.

See

http://www.ph-meter.info/pH-electrode-flowing-gel

for details.

Borek
--
http://www.chembuddy.com/?left=BATE&right=pH-calculator
http://www.ph-meter.info/pH-electrode
http://www.bpp.com.pl/?left=dysleksja&right=dysleksja
http://www.terapia-kregoslupa.waw.pl