High Ph

OK, I really don't understand this statement "You can not check the pH of
RO/DI water, with a pH meter or a test kit." You are measuring the among of
H+ ions in the water. How does the lack of other ions have a negative effect
on the pH measuring? I am working on my post doc... so feel free to use the
big words. Thanks.

Tre'

"Boomer" wrote in message
...
You can not check the pH of RO/DI water, with a pH meter or a test kit.
The pH, what ever
it reads, is meaningless and gives false readings, as there is basically
nothing in the
water for them to respond to or measure.

"This level is by test kit and also digital probe"

1. I doubt it is both the probe ad kit. Check a fresh batch, a L or so, of
seawater mix
with just tap water or distilled to see what you get.

2.What is your Alk. If you have one of those batches with a very high Alk
it might be
pushing your pH up

3. There may be a spot in your tank where the calcareous substrate is
dissolving, pushing
up the pH

4. Heavy algae growth can bring the pH up to 9 with no problem, as the
algae can remove
the CO2, which causes an immediate shift in the pH to go up. This usually
will also show a
low Alk, as the plants now feed off the CO3-- and HCO3- for their CO2
needs. It is the
reason behind Macro-Algae and FW planted tanks to use CO2 injection. Poor
circulation and
gas exchange can make it worse, as the diffusion of ambient air CO2, into
the tank, will
not be able to keep up with the plant demand for CO2



"The PH from your DI resin water could be high
and has basically destroyed your tanks buffering capacity over time."

There is no alk or buffering in RO/DI water, all of it has been removed.
RO/DI units
automatically destroy all your "buffering capacity"



Boomer

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"The PH from your DI resin water could be high
and has basically destroyed your tanks buffering capacity over time."

There is no alk or buffering in RO/DI water, all of it has been removed.
RO/DI units
automatically destroy all your "buffering capacity"



You missed the point. I was pointing out that if the mixed bed resin is
exhausted, not only do you no longer have DI water, but it can be
significantly alkaline or acidic. Therefore the constant addition of
alkaline water which you trust to be pure DI water, and it no longer is,
slowly eats away at the tanks buffering capacity. Once the last of the
buffering salts covert to their basic form, the buffering is gone and the PH
starts creeping up.

I'm sorry but I've seen it happen on a very large scale where a plating tank
was destroyed because the DI water automatic top-off shifted the PH of the
tank.

Robert

"Tre' Landrum" wrote in message
news:5LCid.13517$233.3377@okepread05...
OK, I really don't understand this statement "You can not check the pH of
RO/DI water, with a pH meter or a test kit." You are measuring the among
of
H+ ions in the water. How does the lack of other ions have a negative
effect
on the pH measuring? I am working on my post doc... so feel free to use
the
big words. Thanks.

Tre'


Doesn't metter. If the DI water really is DI, the PH should be exactly
7.00. Although that is almost impossible to attain. DI water starts
absorbing CO2 and the PH starts going down almost immediately unless you
shield the water. If your DI water has a high or low PH, it simply is no
longer DI water, plain and simple (with the exception of CO2 acidification
of course which is reversible).

And as for the PH meters, make sur you calibrate using two buffers. Using
one only moves the response up and down. If it reads 5 at a PH of 6 and 6
et a PH of 7, then adjusting the PH down by 1 unit will bring both PHs in
line. However if it reads 4 in a 6 buffer and 7 in an 8 buffer, then the
slope is also off. Using two buffers allows you to adjust both. Hard to
explain with drawing a picture.

Robert

It is nearly impossible to measure the pH of RO/DI water. It takes both a special probe
and a specially designed cell to even have a chance of getting an accurate result,and just
because your pH meter gives you a reading doesn't mean it is accurate.

The other problem in measurements with RO/DI, is that you can't take a sample and expose
it to air and get an accurate reading. The resisitivity of 17 Meg-Ohm water and the pH
will drop within just seconds after exposure to air due to CO2 dissolution and absolutely
no buffering capacity in the water. To be accurate, any measurements with water 10
Meh-Ohm almost have to be done on-line.

In short there is not enough conductivity for the pH sensor to work.. The reason for
this is that pH is the measure of a specific ion- H+ (and indirectly OH-). The presence of
H+ will reduce resistivity in the water, but so will any other ionic species.

Here is some theory- H2O molecules have infinite resistance. It is ions that cause
solutions to be conductive. Even perfectly pure water has some ions because of the
equillibrium between H2O, H+ (ions), and OH- (ions). The concentration of the ions H+ and
OH- in perfect water is 0.0000001 molar at 25º C. The pH of this water is exactly 7.
Because of the difficulty (impossibility) in the accurate measurement of pH in ultrapure
water, ASTM has at least removed the requirement from the specification for Type I and
Type II deionized water.

There are some max-min pH values for puure waters, that give you ranges of where you might
be.

http://www.cal-water.com/pdf/ConversionChart.pdf

http://www.purite.co.uk/technical/CH...ISED_WATER.pdf

http://www.coleparmer.com/techinfo/t...+of+Pure+Water


I am working on my post doc... so feel free to use the
big words.

OK, you have them

Some more reading make sure you follow all the links

http://www.advancedaquarist.com/issues/feb2004/chem.htm

Feel free to come to our Chem forum if you have any more questions. The link is below


Boomer

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Sorry, but you don't have clue what you are talking about. Seawater has a maximum Bc at a
pH of 6 & 9, as that is what its pKa is, so if the pH was 9 it would have the greatest
ability to withstand a pH shift, as half of the principal buffer is HCO3- and half is
CO3--. The HCO3- acts as the acid and CO3-- is the base.

At any pH there is an exact ratio of CO2 + H20 : H2CO3 : HCO3 : CO3. As soon as RO/DI
water is exposed to air it will pick up CO2 and the pH will fall, the Alk will remain the
same. Below is how mixed bed resins work

http://rip1.wwwcomm.com/resintech/Co...ell%2089-2.pdf


"Therefore the constant addition of
alkaline water which you trust to be pure DI water, and it no longer is,
slowly eats away at the tanks buffering capacity. Once the last of the
buffering salts covert to their basic form, the buffering is gone and the PH
starts creeping up."

Lets be short, explain that in chemical terms and show any ref that states that from
chemical stand point.You won't find one will you. We are always adding basic ion's, such
OH- and is the reason behind adding kalk, Ca(OH)2 so the so called additon would be plus.

Once the RO/DI water is exposed to air and once a seawater mix is added that water it is
buffered and has a pH, what ever it is and a buffering capacity and if it sits its
buffering doesn't change over time by magic.Finally, in a working seawater aquarium the pH
and "buffering capacity" are always working to the down side, low pH and low Alk unless
you add supplements to counter-react it.

"I'm sorry but I've seen it happen on a very large scale where a plating tank
was destroyed because the DI water automatic top-off shifted the PH of the
tank."

That is because you don't understand water chemistry, you are assuming and guessing. You
may want to look up some ref on plating water chemistry, there is tons out there.

Here is a BIG start on reef water chemistry

http://reefcentral.com/forums/showth...hreadid=102605

If you can't see this go here

http://www.advancedaquarist.com/issues/may2002/chem.htm


I have been in this hobby for over 30 years. Most of my post on NG's and internet boards
( see link below) are on water chemistry and I have yet seen any such thing as you claim.
That is because there is no such thing as you claim.....sorry. Feel free to come to our
chem. forum and post what you have said and see what kind of answers you get. I am not a
chemist, although many label me as one. There are a number of chemists on our board with
Ph D's in chemistry. The most well know is on the link above and moderates our forum on
the link below. All see the post on this NG to Tre'

--
Boomer

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" If the DI water really is DI, the PH should be exactly
7.00. Although that is almost impossible to attain. DI water starts
absorbing CO2 and the PH starts going down almost immediately unless you
shield the water. If your DI water has a high or low PH, it simply is no
longer DI water.

That is really not so at all. No RO/DI or any type of filtration gets it to exactly 7.
For all practical purposes RO/DI water has a pH range from 6.2-7.8 and that is
Ultra -Pure @ 18 megaOhms. And I would call that a high pH and low pH. At 16 MegaOhms it
is 6.1- 7.9. So, this "If your DI water has a high or low PH, it simply is no longer DI
water.", really isn't so, as no DI will ever get it to pH 7. You are talking about 100 %
pure water, which is made up of only H3O + and OH- and there is no such thing.

"And as for the PH meters, make sur you calibrate using two buffers. Using
one only moves the response up and down. "

This is no help for measuring RO/DI water

--
Boomer

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"Robert Cadieux" wrote in message ...
:
: "Tre' Landrum" wrote in message
: news:5LCid.13517$233.3377@okepread05...
: OK, I really don't understand this statement "You can not check the pH of
: RO/DI water, with a pH meter or a test kit." You are measuring the among
: of
: H+ ions in the water. How does the lack of other ions have a negative
: effect
: on the pH measuring? I am working on my post doc... so feel free to use
: the
: big words. Thanks.
:
: Tre'
:
:
: Doesn't metter. If the DI water really is DI, the PH should be exactly
: 7.00. Although that is almost impossible to attain. DI water starts
: absorbing CO2 and the PH starts going down almost immediately unless you
: shield the water. If your DI water has a high or low PH, it simply is no
: longer DI water, plain and simple (with the exception of CO2 acidification
: of course which is reversible).
:
: And as for the PH meters, make sur you calibrate using two buffers. Using
: one only moves the response up and down. If it reads 5 at a PH of 6 and 6
: et a PH of 7, then adjusting the PH down by 1 unit will bring both PHs in
: line. However if it reads 4 in a 6 buffer and 7 in an 8 buffer, then the
: slope is also off. Using two buffers allows you to adjust both. Hard to
: explain with drawing a picture.
:
: Robert
:
:

Bob

Sorry if I came out sounding like a horses ass, I usually don't realize it till later and
it is to late. I spent a long time trying to fix this but it always doesn't work. Many of
the guys here know what I mean

--
Boomer

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"Boomer" wrote in message
...
: Sorry, but you don't have clue what you are talking about. Seawater has a maximum Bc at
a
: pH of 6 & 9, as that is what its pKa is, so if the pH was 9 it would have the greatest
: ability to withstand a pH shift, as half of the principal buffer is HCO3- and half is
: CO3--. The HCO3- acts as the acid and CO3-- is the base.
:
: At any pH there is an exact ratio of CO2 + H20 : H2CO3 : HCO3 : CO3. As soon as RO/DI
: water is exposed to air it will pick up CO2 and the pH will fall, the Alk will remain
the
: same. Below is how mixed bed resins work
:
:
http://rip1.wwwcomm.com/resintech/Co...ell%2089-2.pdf
:
:
: "Therefore the constant addition of
: alkaline water which you trust to be pure DI water, and it no longer is,
: slowly eats away at the tanks buffering capacity. Once the last of the
: buffering salts covert to their basic form, the buffering is gone and the PH
: starts creeping up."
:
: Lets be short, explain that in chemical terms and show any ref that states that from
: chemical stand point.You won't find one will you. We are always adding basic ion's, such
: OH- and is the reason behind adding kalk, Ca(OH)2 so the so called additon would be
plus.
:
: Once the RO/DI water is exposed to air and once a seawater mix is added that water it
is
: buffered and has a pH, what ever it is and a buffering capacity and if it sits its
: buffering doesn't change over time by magic.Finally, in a working seawater aquarium the
pH
: and "buffering capacity" are always working to the down side, low pH and low Alk unless
: you add supplements to counter-react it.
:
: "I'm sorry but I've seen it happen on a very large scale where a plating tank
: was destroyed because the DI water automatic top-off shifted the PH of the
: tank."
:
: That is because you don't understand water chemistry, you are assuming and guessing. You
: may want to look up some ref on plating water chemistry, there is tons out there.
:
: Here is a BIG start on reef water chemistry
:
: http://reefcentral.com/forums/showth...hreadid=102605
:
: If you can't see this go here
:
: http://www.advancedaquarist.com/issues/may2002/chem.htm
:
:
: I have been in this hobby for over 30 years. Most of my post on NG's and internet boards
: ( see link below) are on water chemistry and I have yet seen any such thing as you
claim.
: That is because there is no such thing as you claim.....sorry. Feel free to come to our
: chem. forum and post what you have said and see what kind of answers you get. I am not a
: chemist, although many label me as one. There are a number of chemists on our board with
: Ph D's in chemistry. The most well know is on the link above and moderates our forum on
: the link below. All see the post on this NG to Tre'
:
: --
: Boomer
:
: Want to talk chemistry ? The Reef Chemistry Forum
: http://www.reefcentral.com/vbulletin/index.php
:
: Want to See More ?
: Please Join Our Growing Membership
: www.coralrealm.com
:
: If You See Me Running You Better Catch-Up
:
: