Which best TDS EC meter water RO: AP-1 vs AP-2 vs EC-3 vs TDS-3 vs COM-100 year 2019 • HM Digital

Comparing HM Digital AP-1, AP-2, TDS-3, EC-3 and COM-100 meters, water testing, ppm. I test different reverse osmosis water solutions. Conversion factor: 2 µS (MicroSiemens) = 1 ppm.
Comparison: http://purified-water.dk/tds_ec_meters_hm_digital_ap-1_ap-2_tds-3_ec-3.shtml
Buy AP-1 https://purified-water.dk/shop/Extras/meters/AP1
Buy AP-2 https://purified-water.dk/shop/Extras/meters/AP2
Buy TDS-3 https://purified-water.dk/shop/Extras/meters/TDS3
Buy EC-3 https://purified-water.dk/shop/Extras/meters/EC3
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