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Author: Subject: Can't decide which pH meter to get...
Swinfi2
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[*] posted on 25-3-2019 at 05:35
Can't decide which pH meter to get...


So im just going through ebay for simplicitys sake. I already bought a cheap £5 model only to find out how much of a waste of time they are.
I know I could get something reliable like a bluelabs meter but they set you back ~£200.

Can someone recommend me a known good pH meter that isn't £200?
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markx
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[*] posted on 25-3-2019 at 07:06


What kind of an environment are you going to use the apparatus in and in what pH range? And how precise do you need it to be?
For generic purpose I guess getting a better quality aquarium pH monitor type of apparatus could serve pretty well. In the price range of about 50-100$....it's still only half as bad as spitting out 200 :D

E.g. (honestly I do not know if that is a good unit, just an example of the ground I would explore if I needed one):
https://www.ebay.com/itm/PH-EC-Conductivity-Meter-Water-Qual...

I would also suggest to get something with a replaceable electrode and definitely with a decent system of calibration. These things wander and are easy to ruin when subjected to wild swings in pH, or oxydising environments, or mechanical damage, or let dry out for too long inbetween uses. So having an option to just stick a new electrode on the machine is quite essential.




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Sulaiman
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[*] posted on 25-3-2019 at 07:17


If you intend to use your pH meter frequently then I have no useful information.

If you intend to use your pH meter infrequently then I suggest that you buy
pH papers and pigment indicator powders/liquids, because;
. pH probes need great care in use (thin/fragile), or great patience (thick/rugged)
. pH probes need to be stored in a buffer solution
. pH probes need standard reference buffers for calibration

OTOH pH papers are quick and reliable,
and precise (at extra cost of course) if required
and there are a wide range of chemical-specific indicator papers,
and of course individual indicators https://en.wikipedia.org/wiki/PH_indicator

[Edited on 25-3-2019 by Sulaiman]




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morganbw
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[*] posted on 25-3-2019 at 13:22


Quote: Originally posted by Sulaiman  
If you intend to use your pH meter frequently then I have no useful information.

If you intend to use your pH meter infrequently then I suggest that you buy
pH papers and pigment indicator powders/liquids, because;
. pH probes need great care in use (thin/fragile), or great patience (thick/rugged)
. pH probes need to be stored in a buffer solution
. pH probes need standard reference buffers for calibration

OTOH pH papers are quick and reliable,
and precise (at extra cost of course) if required
and there are a wide range of chemical-specific indicator papers,
and of course individual indicators https://en.wikipedia.org/wiki/PH_indicator

[Edited on 25-3-2019 by Sulaiman]


^^this^^
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BromicAcid
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[*] posted on 25-3-2019 at 17:27


The big thing is if you're trying to measure the pH of something darkly colored. In that case.

Meter = Great
Paper = Crap

How often are you checking pH? That's the other thing you should be asking yourself. If you're just quenching / neutralizing things sometimes all you need is the right indicator.




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Swinfi2
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[*] posted on 26-3-2019 at 15:41


Thanks markx I remember using that style meter at uni and aside from the extra calibrations they are good at their job. Just wish I'd seen them last time I looked (I had international shipping off).

I suppose it depends on how much I'm doing in the lab/shed but I'd say not too much pH swings 7+-2 and idk I'm out about 2 times a week trying to get a handle on how electrolysis works and regenerate some supplies.

Well it used to be that until my clay pot broke from being mistreated.

[Edited on 26-3-2019 by Swinfi2]
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Sulaiman
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[*] posted on 26-3-2019 at 15:55


I doubt that you can easily measure pH in an active electrolysis cell due to the electric potential gradients in the electrolyte(s),
an electrolysis cell is an excellent place to use pH sensitive pigments as you can see in 3D the pH gradients.
(if the electrolyte is transparent and not too coloured)




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markx
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[*] posted on 29-3-2019 at 10:20


Quote: Originally posted by Swinfi2  
Thanks markx I remember using that style meter at uni and aside from the extra calibrations they are good at their job. Just wish I'd seen them last time I looked (I had international shipping off).

I suppose it depends on how much I'm doing in the lab/shed but I'd say not too much pH swings 7+-2 and idk I'm out about 2 times a week trying to get a handle on how electrolysis works and regenerate some supplies.

Well it used to be that until my clay pot broke from being mistreated.

[Edited on 26-3-2019 by Swinfi2]


I hope it is not a chlorate or other halide electrolysis that you are trying to monitor with the pH meter?....because you can forget about that approach. The cell liquor will kill the electrode within a very short time. And it shall not show anything informative.




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Swinfi2
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[*] posted on 31-3-2019 at 05:28


Nah, the plan is to regenerate H2SO4 from its sodium salts. Which for some reason last time started turning the solution purple and eating my lead bar and clay pot hence using a meter to get a handle on progress (and not stupidly overshoot the endpoint which imo partly caused my issues).

I do plan on keeping the solutions relatively dilute too, so the meter lasts longer.
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Sulaiman
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[*] posted on 31-3-2019 at 06:57


Even IF a pH meter worked well in the planned environment,
do you need an accurate pH measurement ?
the cheapest pH papers on eBay (the ones that I use most) give +/- 1 pH unit easily,
which should be sufficient ?




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