Prices of conductivity meters vary widely. Here we report the response time, stability, and linearity of five meters.
The Hanna HI 98188 and the YSI Pro 30 are the two most expensive meters and they were the most stable. They were within 5% of the actual conductivity.
The Blue Pen was consistently closer to the actual conductivity than the other two Hanna meters and at only $20 it is a cost effective meter.
Rhoades, SaundraLyn G. and Bugbee, Bruce, "Evaluation of Five Conductivity Meters" (2015). Techniques and Instruments. Paper 13.