homebuilt vAg electrode?

Well, the restriction on the length of exposed plated Silver is not a hard and fast rule.

Also, the HANNA meter electrode is not ideal for this measurement. My RE is a HANNA Ag/Ag/Cl electrode build as a RE and it works fine.

PE

I used to perform Total Organic Halide analysis, and we had a silver electrode in it that we would clean using Ajax Powder, which has chlorine in it, well, probably as chloramine-T which releases free chlorine in water solution. The Ajax was nice as it had fine grit for scrubbing the crap off the silver electrode and I'm sure plated it somewhat as well!