Strange PH

[Skipp]

When I measure my PH with a American Marine probe,It says the PH is
7.77.With a Salifet or Red Sea test kit It says 8.1.I have recalibrated the
probe twice with 7.00 & 10.00 and replaced the probe.My fresh water tank
reads 7.3 Marine tank 7.77.New salt mix is about 7.78.I keep the specific
gravity sat 1.023..Any help would be appreciated.
Skipp

[Pszemol]

"Skipp" > wrote in message ...
> When I measure my PH with a American Marine probe,It says the PH is
> 7.77.With a Salifet or Red Sea test kit It says 8.1.I have recalibrated the
> probe twice with 7.00 & 10.00 and replaced the probe.My fresh water tank
> reads 7.3 Marine tank 7.77.New salt mix is about 7.78.I keep the specific
> gravity sat 1.023..Any help would be appreciated.

Correctly calibrated electronic meter will be more acurate than color test.
Your ability to read color and comare it with a template is worse than
the acuracy of electronic pH meter, so I would trust the meter if calibrated.
Also, color test may be just old, expired, incorrectly stored, etc.

[Pszemol]

"Pszemol" > wrote in message ...
> "Skipp" > wrote in message ...
>> When I measure my PH with a American Marine probe,It says the PH is
>> 7.77.With a Salifet or Red Sea test kit It says 8.1.I have recalibrated the
>> probe twice with 7.00 & 10.00 and replaced the probe.My fresh water tank
>> reads 7.3 Marine tank 7.77.New salt mix is about 7.78.I keep the specific
>> gravity sat 1.023..Any help would be appreciated.
>
> Correctly calibrated electronic meter will be more acurate than color test.
> Your ability to read color and comare it with a template is worse than
> the acuracy of electronic pH meter, so I would trust the meter if calibrated.
> Also, color test may be just old, expired, incorrectly stored, etc.

One more thing - sometimes there are some stray electric currents
in the water column which might interfere with the pH meter readings.
You can verify if this is your case very simply - just take a water
sample into a clean glass cup and measure pH with the probe outside
of the tank. If the reading be the same I would trust the meter.

[Toni]

"Pszemol" > wrote in message
...
> One more thing - sometimes there are some stray electric currents
> in the water column which might interfere with the pH meter readings.
> You can verify if this is your case very simply - just take a water
> sample into a clean glass cup and measure pH with the probe outside
> of the tank. If the reading be the same I would trust the meter.




Also- many folks report problems when using the AC adapter to power the
thing.
Battery powered units usually behave much more reasonably.


--
Toni
http://www.cearbhaill.com/reef.htm.

[RicSeyler]

I agree,
I never got my Pinpoint A/C adapter to work properly, (erratic readings)
I had to use battery.

Toni wrote:

>"Pszemol" > wrote in message
...
>
>
>>One more thing - sometimes there are some stray electric currents
>>in the water column which might interfere with the pH meter readings.
>>You can verify if this is your case very simply - just take a water
>>sample into a clean glass cup and measure pH with the probe outside
>>of the tank. If the reading be the same I would trust the meter.
>>
>>
>
>
>
>
>Also- many folks report problems when using the AC adapter to power the
>thing.
>Battery powered units usually behave much more reasonably.
>
>
>
>

--
Ric Seyler

[Koded-Sophism]

I'm not am not electrical design engineer but I think you need three prongs
on an AC adapter that is going to measure a signal, or produce signal.
Other wise you get interference in the signal.


Examples and Explanation:


Turn tables have a grounding line. Because other wise the AC makes a hum
over the speakers. Same applies to lots of pro audio gear.

You could try, if the unit has any exposed metal, duck taping a copper wire
(exposed speaker wire will work, is cheap, and can be purchased at radio
shack) to the unit, then wrapping it around a metal (copper preferred) pipe.

Why this doesn't happen with a battery? A battery has a built in ground,
that's what the negative side is. So you don't get a "hum" so to speak.
The ground soaks up all the excess signal.

-Koded


"RicSeyler" > wrote in message
t...
I agree,
I never got my Pinpoint A/C adapter to work properly, (erratic readings)
I had to use battery.

Toni wrote:

"Pszemol" > wrote in message
...

One more thing - sometimes there are some stray electric currents
in the water column which might interfere with the pH meter readings.
You can verify if this is your case very simply - just take a water
sample into a clean glass cup and measure pH with the probe outside
of the tank. If the reading be the same I would trust the meter.





Also- many folks report problems when using the AC adapter to power the
thing.
Battery powered units usually behave much more reasonably.





--
Ric Seyler

[Pszemol]

"Toni" > wrote in message ...
> Also- many folks report problems when using the AC adapter
> to power the thing.
> Battery powered units usually behave much more reasonably.

This can be a problem ONLY with poorly designed meters.

I am using two Thermo Orion units (models 420A and 520A)
and both on AC adapters - no such problems observed...
They are made in early 90's have over 10 years of service.
Highly recommend - very good meters with RS232 for a printer
or a pc used as pH recorder/controller.

[Skipp]

I am using a battery.All my reef inhabitants are doing just great.That is
what makes me wonder about the meter reading.I have spoken at length with
the people at American Marine.One thing I forgot to mention was if I add
Bicarb of Soda to raise the PH it actually lowers the reading.
Skipp

[Pszemol]

"Skipp" > wrote in message ...
> I am using a battery.All my reef inhabitants are doing just great.That is
> what makes me wonder about the meter reading.I have spoken at length with
> the people at American Marine.One thing I forgot to mention was if I add
> Bicarb of Soda to raise the PH it actually lowers the reading.

One more thing...
Are you sure you are measuring pH at the same time during day?
You might have large pH swings between night and day - in my
tank I observe a swing from pH=7.79 morning to pH=8.35 evening.
And this is with very high alkalinity, so I do not quite understand.

[Soji John]

Skipp wrote:

>I am using a battery.All my reef inhabitants are doing just great.That is
>what makes me wonder about the meter reading.I have spoken at length with
>the people at American Marine.One thing I forgot to mention was if I add
>Bicarb of Soda to raise the PH it actually lowers the reading.
>Skipp
>
>
>
>
Baking soda will initially drop the pH. It will then rise over a period
of 24 hours rising above the pH before you added the baking soda. The
drop in pH can be reduced by baking the baking soda in an oven (300 deg
C for 1 hour is what I use).
-soji

[Boomer]

1. Have you checked your meter and test kits elsewhere ? A friends house, LFS etc..

2. Some salt mixes may mix to 7.8, it depends on the amount of ambient air CO2. Usually
they don't and mix high and then drop to about 8.2. Take a sample and aerated if for 24
hr, use outside air and check the sample with all three again and see what you get.

3. Your SG is to low, needs to be around 1.025 @ 82 F

4. A sort test. Take a liter of water and add some SeaChem Labs "Marine Buffer" , about a
"pinch" of it. The pH should be around 8.3 only all three tests. Or on a one shot deal,
add about 1 level teaspoon to 20 gals of water, will give the same 8.3 pH.

Also, as soji as said

"Baking soda will initially drop the pH. It will then rise over a period
of 24 hours rising above the pH before you added the baking soda. The
drop in pH can be reduced by baking the baking soda in an oven (300 deg
C for 1 hour is what I use). "

There are other more complicate pH issues. pH measurement is affected by "salt" , by
meters and many test kits. Such errors may show the difference you see. Normally the
errors are about the same so it is not a issue per say. However, if the pH test kit has a
+ error, ie., pH 8.1 and is not error corrected for, we will say its .55, then 8.1 - .55
= 7.6. pH real pH of the test kits. pH meter error corrected 7.77 -.15 = 7.6 pH. So they
are the same. I highly doubt this is the issue, as an error of .55 is very large and Habib
from Salifert, would never use a pH indicator with such a error, without saying so or how
to correct it. The biggest error I have seen on a pH test kit is .30, from La Motte's
kit but the tell you how to correct the error. It may be, by chance, that you just have
two bad kits

Boomer

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