Solution to store PH probe

[Rothie]

I just purchased a Hanna instruments PH meter with a gel-filled probe. The instructions say to store it in a special storage solution made be Hanna. The Hanna web site doesn't say what this solution is made of, and it also says "do not use distilled or DI water for storage purposes". I can't find a place to purchase this solution. What are my alternatives for storing solution. I use the probe on several tanks and would like to store it in between uses.

[Andrewsreef]

I have a Milwalke PH51 pen I just got. It also says you have to store it in the solution. The rep from the company said distilled water was fine. Not sure on yours though.

Andrew

[Rothie]

Thanks,Andrew. I'll see what other responses I get, and maybe come up with a consensus.

[Euclid]

If you have a Hanna pHep meter you can store it with a small amount of pH 7 calibration fluid (rather than storage solution) ... Hanna recommends using their calibration fluid (HI 7007) but I'm sure that any pH 7 calibration fluid would work equally as well.

As far as the use of distilled water goes I think the main danger (and the reason why most companies don't recommend using it) is turning on the probe while its in the distilled water. This would most likely cause damage to the circuit(s) connected to the electrode. (So I guess as long as the probe isn't turned on while in storage using distilled water shouldn't be much of a problem)

Corbin

[Boomer]

Most, proper, pH storage solutions, are a special buffered solution of KCl 4 Molar strength. Some manufactures do say pH calibration buffer or distilled water

[Randy Holmes-Farley]

The idea of the storage solutoions is to keep the fluid inside the probe in approximate equilibrium with the outside solution. That way, there is not an osmotic driving force for the ions to leach out. Hence the solution that Boomer recommended.

I wouldn't store them in RO/DI because that will give the biggest osmotic difference. A pH buffer, maybe even with some table salt added would be fine if you don't want to spring for the commercial fluid.

FWIW, my probe never leaves the tank water except during calibration.