gcvt420

I wondered the same thing when I was researching the Bluelab. I emailed them about it and they directed me to this page on their website: http://www.getbluelab.com/Support/Understanding+what+ppm+scale+to+use.html

Hope that helps!

hey just had a question for you about the blue lab combo meter. its says ppm 500, does that mean you multiply the ppm reading by 500? do you use the ppm setting of the ec? any advice would be greatly appricated.

thanks in advance