I did calibrate it with EC solution and got the correct reading. So I want to make sure I understand this:

Since I calibrated it using EC and it read the correct reading in the solution, then the PPMs are correct?

If that is the case then why doesn't a known solution of 1500ppm read as 1500 ppm when calibrated correctly with EC solution? Or is the 1500PPM solution used to calibrate only PPM?

An example would be since I calibrted with EC and got the correct reading. Wouldn't my PPM of a known PPM solution be 1500 instead of 1200PM?

Thanks,

P