If you try it, please report back.Anyone tried this one ?
2310-C High-Range Conductivity Electrode (K=10, BNC Connector)
Apera Instruments 2310-C Conductivity Electrode is designed for high-range conductivity measurement (up to 2,000 MS/cm, K=10.0). Equipped with Apera's unique sensor ring coated with platinum black, the electrode provides a stable and accurate measurement in high range conductivity. The accuracy...aperainst.com
I just installed This $33 one from AliExpress and it works but isn't too accurate (off by about 1.5 psu) and bounces around a bit.