PPM , what’s the lowdown?

What am I measuring…. The soil or the water or both? What are the good numbers and how are they adjusted. I have a meter

PPM literally means parts per million. It’s measuring whatever in water. It doesn’t matter if we are talking about chlorine in city tap water, or plant food added, in the case of plant food added to water we generally have a dosage chart giving us measures in teaspoons per gallon, simply a convenient mixing method, but there is also usually a conversion instruction that gives us the parts per million concentration. How much is needed is another story. That depends on many factors, but PPM simply means parts per million, and is a measure of concentration of a solution. It’s easiest to think of in metric units, where everything is orderly. One milliliter of salt added to a liter of water is one per one thousand, or 1000 per million, or 1000 ppm.

It’s more difficult to wrap your head around using imperial units like ounces and teaspoons, but it’s still concentration of solution, parts per million.

So talk to me about ppm in a soil grow. In the runoff – wouldn’t the solid totally skew the ppm “actual” reading of TDS.

Yesterday I watered to runoff and got some numbers. Do you see anything alarming? What should I infer from all of this? I need to take a nutes/tds course.

White widow auto, 11 weeks, flowering, soil FFHF+FFOH+Pearlite. Have been using Homegrown Standard nutes and some cal mag.

30 ppm in 6.4 pH in.

  • Out #10 2401 ppm 6.2
  • #9 Aggie 877 ppm 6.6
  • #11 1555 ppm 6.3 out
  • #6 1080 ppm 6.13
    #8 60 ppm in 6.3 pH in - 1976 ppm out 6.0 pH out