also... if your looking for a ppm meter. Cheap and works very well.
http://www.amazon.com/HM-Digital-TDS-EZ-Tester-Purity/dp/B001UUN6VO
$20. I've had mine for 7 months, zero fails, no calibration needed. I have a 342ppm solution to check now and again, it varries 5-10ppm above actual...