Which TDS meter is correct?

[USCGRetiredJosh]

So I bought a dual tank water deionizer and it came with a free TDS meter, so I decided to compare it to the other fee one I got with a water pitcher. The way I see it, I still have hard water before I use the deionizer system. I haven't used the deionizer yet, hopefully tomorrow.

[TheWolf]

Quite a bit of difference there.  Put them both in distilled water and see which one reads 000.

 

You can also get a calibration solution to check the meters.

 

http://www.amazon.com/HM-Digital-C342-Calibration-Solution/dp/B001VE99X8/ref=pd_sim_86_2?ie=UTF8&dpID=41Q43Q12WvL&dpSrc=sims&preST=_AC_UL320_SR168%2C320_&refRID=06ESNJ0123N376HDSP1R