What is 3NKCL solution for pH meter
Hello,
The manual for the Gravity analog pH meter at:
https://wiki.dfrobot.com/Gravity__Analog_pH_Sensor_Meter_Kit_V2_SKU_SEN0161-V2
says you need to immerse it in “3NKCL” solution for 8 hours before use.
What is this solution and where can I buy it?