Reliable pH test equipment?

[removedacct1]

I have two different pH test strip kits and discovered today that they give very different pH readings when I tested my silver bath (Wet plate bath).
I've read some reports that electronic pH meters are NOT useful for testing the pH of a silver nitrate solution (something about the nature of the electrode that gets confused in the presence of silver nitrate). So can anyone recommend a RELIABLE, accurate tool for testing pH of a silver nitrate solution? Thanks.

Paul

 

[lantau]

You need a meter with external connection for changeable electrodes. It's probably best not to save on quality. It should also allow connection of a temperature probe and do automatic temp compensation.

Then you'll need to find an electrode for it that can tolerate Silver ions. Don't remember the term for it, but they have two chambers with different electrolytes to prevent silver from reaching the inner one with KCl. That would cause precipitation of AgCl.

The maker of my meter doesn't sell these electrodes anymore, but I'd guess I could connect any other suitable one with BNC connector. I don't need to monitor the pH of my used fixer. That's why I use a standard glass electrode. Colour developer shouldn't accumulate silver. I hope...