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Re: pH meter resuscitation

Matt wrote:
> same general area as the pH test kit results. My question is, I remember
> reading sometime ago about a method for reactivating worn out probes by
> soaking them in a solution of (could have been) KCl. Do those who know, think
> that this will be necessary for these meters? 

I'd recommend it.   

Here's the procedure Andrew Bolling sent to me:
You can rejuvenate an old probe by soaking it PH 4 calibration fluid, or,
as I did, use a cup of water with several drop of Sulfuric acid (battery
acid) mixed in.  (Other acids will work as well, like HCl)  Let it soak
overnight in the acid, followed by a soak in some PH storage solution
(saturated potassium chloride solution) or PH 7 calibration fluid.   Then
it's practically good as new!!  Avoid splashes and protect your skin/eyes
with gloves and glasses.  Calibrate your meter afterwards.  It should
once again be speedy and responsive.  Wright Huntley likes to boast about
the fact that he's had his probe for years and years.  If you're a purist
though, you'll probably want to replace it with a new one every 1.5 years
or so.

In place of the sulfuric acid, I used a dilluted vinegar solution, and it
worked well.   I used 1/3 vinegar, 2/3 water.   I allowed it to soak 
overnight in that solution.  

If there is lots of crud built up on the sensor, use a toothbrush to clean
it up after the acid soak. 

I know it's not an issue in your case, but if anyone is a probe on a pH
controller for CO2, then I'd be careful, since a faulty probe could kill fish.  
Better to just buy a new probe than risk it.  

Chuck Gadd