m0useanswered grow question 3 years ago If you need less of a ppm. Dump some out and add more water if you at your max.
Or add more feed is you need more PPM.
PPM is parts per million of a dissolved measurable solid that conducts electricity.
Somethings added into the water will not add up the PPM as they do not conduct a current.
all PPM pens are TDS meters designed to measure EC.
How it coverts EC to PPM is another thing.
Good Luck!