Question about a reading. I just bought a meter and tested some run off water from one of my auto strains. This will be the second time I’ve introduced nutes to the soil. First time was 1/16 dose. This time was 1/8 dose. Added some cal mag this time and only got a reading of about 450 ppm. My run off reading was nearly 1500. How so high when I’ve put next to nothing in it. My water tests at about 110 ppm. Plant looks healthy