How to read PPM meter blue lab???

I am not sure how to get a reading on my blue lab ppm meter. I have cleaned, and calibrated it in 2.77 ec solution. I keep getting a 0 ppm reading when I test my resevoir. It is plain ph'd tap water. My plant is only a tiny seedling. Today I changed resevoir water, and added a small amount of cal mag and fulvex (4ml total 2ml each) to the water for some nutrition, no base nutrients. PPM meter still gives a zero reading? Do I have too little supplement in my 4 gallons of water, for a reading, or am I doing something wrong?

It probably is to little. I Have the combo meter and I don't get much of a reading when adding bennies.

Should have a reading on your tap water alone, mine is 390ppm...and when i take my bluelab guardian ec meter out of solution it gives all kinds of readings. If it is constantly 0, i would think perhaps something is not functioning correctly and i would contact bluelab or the place you purchased it at.

Something is wrong. Tap water will definitely register some ppm. I have a guardian meter and it has read as low as 30ppm with ro water.