HI98301P TDS Tester with ATC, 1999 ppm (mg/L) - Hanna Instruments 
 
HI98301P is rugged and reliable pocket-sized testers that offer quick and accurate reading of TDS. HI98301P has manual calibration faccility and it can measure TDS upto 1999 mg/L (ppm)
Graphite electrodes
ATC 
Simple one point calibration
Easy to use
Economical
 
Details
The DiST® family of testers is widely used for monitoring EC/TDS in drinking water, water conditioning, reverse osmosis, cooling towers, wastewater, laboratories, agriculture, aquaculture and aquariums, hydroponics and the printing industry.
HI98301P can measure TDS upto 1999 ppm
 
These testers feature an amperometric graphite electrode that provides better repeatability in measurements since they do not oxidize. An amperometric measurement of EC/TDS is based on Ohm’s Law, I = V/R where R depends on the distance between two pins and their surface. Oxidation changes both the distance and surface which will affect accuracy. The DiST’s non-oxidizing graphite pins are able to provide an optimal surface for accurate, dependable results.
 
When calibration is necessary, simply submerge the electrode tip into calibration solution (1382 ppm) and adjust the trimmer on the side of the tester.