Dual inlines lack the accuracy of a good handheld, you took a step backwards. I have two dual inlines and don't even turn them on, they never agree with the better handheld which is actually temperature compensated. The handheld is telling you the truth, the inlines are ballpark close.
I'm sure you don't want to cut you inline probes up but if you look at the fatter part of the probe there is a little rectangular hole or cut out in the pastic. Inside that hole, exposed to air, not water, is the temperature probe which does the temperature compensation and correction for the TDS reading. Unless the air temperature and wate temperature are exactly the same the meter can be significantly off, something like 2% for every degree C they differ.
The better handhelds like the HM Digital TDS-3, TDS-4TM, COM-100 and their new AP series are truly temperature compensated since the probe sticks in the water and they have a digital temperature read out too and are extremely accurate. In the case of the COM-100 it reads down to a tenth of a ppm TDS unlike hardly any other hobbyist grade meter.
The inlines also depend on flow past the probe inside the tee, must be rotated in the corrct direction and cannot be used portable so are dedicated to two places, usually RO only and final permeate or RO/DI. To troubleshoot a RO/DI system you need three readings, those two plus the tap water TDS to determine the rejection rate so you need two dual inlines or they now have a three probe model but it still lacks the accuracy of the ATC handhelds. You can't just dip the probe of an inline in a glass of water, it has to be flowing in a laminar pattern past the probe in the right direction. The handheld can be used anywhere including your ATO storage, the LFS water, bottled water, vending machine water, your buddies house etc and is pretty rugged.
No comparison.
I'm sure you don't want to cut you inline probes up but if you look at the fatter part of the probe there is a little rectangular hole or cut out in the pastic. Inside that hole, exposed to air, not water, is the temperature probe which does the temperature compensation and correction for the TDS reading. Unless the air temperature and wate temperature are exactly the same the meter can be significantly off, something like 2% for every degree C they differ.
The better handhelds like the HM Digital TDS-3, TDS-4TM, COM-100 and their new AP series are truly temperature compensated since the probe sticks in the water and they have a digital temperature read out too and are extremely accurate. In the case of the COM-100 it reads down to a tenth of a ppm TDS unlike hardly any other hobbyist grade meter.
The inlines also depend on flow past the probe inside the tee, must be rotated in the corrct direction and cannot be used portable so are dedicated to two places, usually RO only and final permeate or RO/DI. To troubleshoot a RO/DI system you need three readings, those two plus the tap water TDS to determine the rejection rate so you need two dual inlines or they now have a three probe model but it still lacks the accuracy of the ATC handhelds. You can't just dip the probe of an inline in a glass of water, it has to be flowing in a laminar pattern past the probe in the right direction. The handheld can be used anywhere including your ATO storage, the LFS water, bottled water, vending machine water, your buddies house etc and is pretty rugged.
No comparison.
I may have let it dry. I'm not sure.
