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Date: 13 Feb 2005 22:10:09
From: Nikki Casali
Subject: pH probe maintenance
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How often should continuous pH probes be cleaned and with which
solutions? How long do you leave the probe in the cleaning solution?
Should you place the probe in a storage solution after?
How about refillable probes and how often do they need refilling?
How do you calibrate yours?
Nikki
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Date: 14 Feb 2005 11:10:53
From: Rick
Subject: Re: pH probe maintenance
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"Nikki Casali" <nikki@ncSasPali.deAmoMn.co.uk > wrote in message
news:cuoj80$8hn$1$8300dec7@news.demon.co.uk...
> How often should continuous pH probes be cleaned and with which
> solutions? How long do you leave the probe in the cleaning solution?
> Should you place the probe in a storage solution after?
>
> How about refillable probes and how often do they need refilling?
>
> How do you calibrate yours?
>
> Nikki
PH 4.0 calibration solution is acidic so I simply leave my Hanna meter
sitting in that solution for an hour or so after I calibrate. My first meter
stopped calibrating and the cause was a dirty probe likely from a green
water outbreak I was having at the time. Rinsing in tap water did not clean
the probe sufficient enough. When I talked to a tech guy at Hanna he
recommended using acid or leaving it in the solution.
Rick
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Date: 14 Feb 2005 06:45:25
From: Margolis
Subject: Re: pH probe maintenance
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I just rinse it off under the running tap once every 4-6 weeks. No need to
put it in storage solution, just put it back in the tank..
as for refilling them, what would you fill it with? They don't have
anything in them to refill.
and for calibration, just get yourself some calibration fluid and use it
according to the directions on the ph meter. I use 4 and 7. I put it in
the 7 and then adjust the 7 screw until it is correct and then use the 4 and
adjust the 4/10 screw until it is correct. Rinse with ro or distilled water
between testing fluids. If you don't have ro or distilled water just rinse
it under the tap and make sure you shake it dry.
--
Margolis
http://web.archive.org/web/20030215212142/http://www.agqx.org/faqs/AGQ2FAQ.htm
http://www.unrealtower.org/faq
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Date: 14 Feb 2005 16:23:10
From: Nikki Casali
Subject: Re: pH probe maintenance
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Margolis wrote:
> I just rinse it off under the running tap once every 4-6 weeks. No need to
> put it in storage solution, just put it back in the tank..
I got algae growing on mine. I had to soak it in acid to clean it. I've
heard some using 1:9 bleach and water solution.
>
> as for refilling them, what would you fill it with? They don't have
> anything in them to refill.
>
My Aqua Medic probe has a refill hole. Once enough reference solution
has leached out after months of use, it can be refilled with 3.5 M
KCl/AgCl instead of buying a new one.
> and for calibration, just get yourself some calibration fluid and use it
> according to the directions on the ph meter. I use 4 and 7. I put it in
> the 7 and then adjust the 7 screw until it is correct and then use the 4 and
> adjust the 4/10 screw until it is correct. Rinse with ro or distilled water
> between testing fluids. If you don't have ro or distilled water just rinse
> it under the tap and make sure you shake it dry.
>
I use 7 and 9.18. Every time I recalibrate, the probe presents an
artificially low reading in the tank. It takes an hour to drift from the
6.85 to the correct 7.15. It's a new probe. I've heard someone else with
a similar experience at http://www.thekrib.com/Chemistry/ph.html.
Nikki
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Date: 13 Feb 2005 23:05:18
From: George Pontis
Subject: Re: pH probe maintenance
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In article <cuoj80$8hn$1$8300dec7@news.demon.co.uk >, nikki@ncSasPali.deAmoMn.co.uk
says...
> How often should continuous pH probes be cleaned and with which
> solutions? How long do you leave the probe in the cleaning solution?
> Should you place the probe in a storage solution after?
Aquarium water is fairly benign for a pH probe. Perhaps a bit of organic buildup
over time. I would go with mfg's recommendation since probe materials vary. A
rinse with clean water is usually good enough before storing a probe. If the probe
is allowed to dry out it will take a while to rehydrate before it regains full
accuracy.
> How about refillable probes and how often do they need refilling?
>
Depends on several factors, including the volume of the reservoir and the
elevation of the fluid in the reservoir compared to the sample (aquarium water
level). It is very important to maintain the reservoir level above the sample
fluid level so there will be a continuous, slow flow of reference solution out
through the porous glass frit. The response of the probe depends on this.
BTW, the reference solution is typically an aqueous solution of potassium and
silver chloride.
> How do you calibrate yours?
With pH reference solutions, available from places like Omega or almost any
chemical supply place. They are usually available in pH 4, 7, and 10. Often it is
only necessary to get 7 and one of the others. Cost is about $5 per pint and they
are easily shippable.
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Date: 14 Feb 2005 17:02:03
From: Nikki Casali
Subject: Re: pH probe maintenance
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George Pontis wrote:
> It is very important to maintain the reservoir level above the sample
> fluid level so there will be a continuous, slow flow of reference solution out
> through the porous glass frit. The response of the probe depends on this.
Good point. I never thought of that.
Nikki
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