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14-02-2005, 07:05 AM

In article ,
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.