EC and PPM

I am having a heck of a time with EC. I am using foxfarm nutes.

It seems that when I add nutes the EC goes up and I am finding it impossible to hit target numbers on the EC while hitting target number with PPM. It’s either I go low on Nutes to hit EC or it just won’t happen.

Are there any tricks I can use to lower my EC while maintaining proper PPM for my stage of growth?

I am doing DWC.


EC is a Calculation of PPM…PPM is one of two standard scales 500 or 700. Just Use EC its universal. I can get you the calculations if you want to make life difficult.

  • EC = Electrical Conductivity.
  • PPM = Parts Per Million.
  • TDS = Total Dissolved Solids.
  • All meters/pens measure EC. …
  • EC X 700 = PPM 700; Example: 1.00 EC = 700 ppm.
  • Or 1.3 EC x 700 = 910 ppm.
  • EC X 500 = TDS (or PPM 500); Example: 1.00 EC = 500 ppm.
  • Or 1.3 EC x 500 = 650 ppm.

Shows how much I know. Can I just hit target ppm? In their week the ppm is around 1000 I am doing around 800 because that seems hot. But my EC is reading like 2.43.

Where it supposed to be around 1.2 or something.


Yes, you just need to know which scale you are functioning on.
2.43 x 500 = 1215ppm
2.43 x 700 = 1700ppm
…Measure just your water source no nutes…mine is 300 this time of year. If I subtracted my water alkalinity I’d be 900 or 1400…If you’re using RO…just add more water, that’ll dilute your mix. So will tap/well but it always has that carbonate/bicarbonate component.



Its a TDS so its 500 scale…Why is that LED segment on the 1 out, did you send it in the drink? If so, buy a new one, those are not waterproof - one dunk and done.

So 610/500 = 1.2 EC… thats cool.
In all honesty I’d be feeding harder than that, but I’ve been at this a while and I dont know squat about your exp. or setup.