Need to reclaibrate my TDS monitor on my RO/DI unit. It is a HM Digital, DMI In-line Dual TDS meter. Instruction booklet has no information, except "Calibrate with NaCl". The unit is approx. 1 1/2 yrs old. The unit use to read 000 ppm, now read 002 ppm and does not go below this. All cartridges are new.
Last edited:
