ORP standard solutions allow you to test the precision of ORP electrodes. For example, by immersing the electrode in HI 7022 solution, you should read 470 mV @ 25°C/77°F
If the reading is outside the indicated interval, clean and condition your ORP electrode in HANNA® pretreatment solution. Use HI 7092 for oxidizing or HI 7091 for reducing pretreatment.
HI991301 Multiparameter pH/EC/TDS/°C - EC to 20.00 mS
BL983327-1 EC Mini Controller upto 10.00 mS/cm, 230V
HI717 Checker HC ® - Phosphate, HR 



