as a responsible company, we also buy samples and test the products for several months, before we introduce the product and re-sell it in our country..because we do not want to sell failure products, customers will get disappointed and finally we will get the lost of the money..
we calibrated five times the NEW 4 unit and have the stable and correct reading with the calibration solution.
but when we put all electrodes in to the same water, the 4 unit gave false reading,
the pH read was 6,compare with liquid pH tester was around 7 and other monitor read 7.31
the ORP read was wrong too, 38-39, while other monitor read 145
so we complained to the ZD company, they said we need to return the 4 unit to them for their checking, after they received the 4 unit, they said the 4 unit are alright no factory failure.
but until now, May 2016 they do not give back the unit to us or replace with the new units or refund our money ( total USD.250 )
So...IF you are an end user and buy only 1 unit, you WILL NEVER KNOW, IF your unit is reading correctly or false...
so you should always re-check the water with other method or other meter.
ZD Instrument Co Reviews
Www.zdinstrument.com
as a responsible company, we also buy samples and test the products for several months, before we introduce the product and re-sell it in our country..because we do not want to sell failure products, customers will get disappointed and finally we will get the lost of the money..
we calibrated five times the NEW 4 unit and have the stable and correct reading with the calibration solution.
but when we put all electrodes in to the same water, the 4 unit gave false reading,
the pH read was 6,compare with liquid pH tester was around 7 and other monitor read 7.31
the ORP read was wrong too, 38-39, while other monitor read 145
so we complained to the ZD company, they said we need to return the 4 unit to them for their checking, after they received the 4 unit, they said the 4 unit are alright no factory failure.
but until now, May 2016 they do not give back the unit to us or replace with the new units or refund our money ( total USD.250 )
So...IF you are an end user and buy only 1 unit, you WILL NEVER KNOW, IF your unit is reading correctly or false...
so you should always re-check the water with other method or other meter.