Questions about PPM on starter soil

I have some autos in fox farms starter soil + perlite. They are 25 days from seed. I always test PH of runoff and it stays about 5.8. I water with 6.0 PH. I have used no nutrients yet.

I got a PPM + EC Meter and just got these results:

  • Distilled water: 2 ppm
  • Tap Water (Hard, Phoenix AZ high in mag & cal) 600 PPM
  • Runoff from plant soil = 3502 ppm!!!

This soil is at the right PH, the plants look great to me, and I’ve added zero nutrients since I scooped it out the bag.
Should I be worried or is this OK?
Thanks in advance


This is most interesting. How are you collecting your runoff? I wouldn’t be concerned only because you’re asking questions and that’s the right thing to do.

It sounds as if there is a salt buildup but that just doesn’t add up with the rest of the data you provided. 600 ppm is about right for Mesa water, but if I add 1/8th teaspoon of salt to it, it will bounce up to 3000 quick. Again, your timeline and scenario don’t seem to support the salt buildup theory however.

Best wait for the elders to respond: @PreyBird1 @sssportsmfg @happilyretired and others…


Um that soil is hot from the get go. Gonna be hard to ppm runoff on hot soil!


Is this what your talking about?


I have a metal baking sheet, put the canvas grow bag on the sheet, water the plant, and then dump the water from the metal sheet into a small glass and test it there. If there’s 3 cups of runoff I’m getting the first cup.


How much run off? Needs to be like 10% of wht you put in for correct reading.


Is there a video or something? Srsly I am not picturing this.


I tried fox farm once! It was ocean forest and i got fungus gnats immediately. Havent used it since never has gnats after that but also learned about fungus gnats and tried to be consistent with waterings and water amounts.


Well say you have a quart of water. After pouring in the water youd want to see 10% of 1 quart come back out on the metal tray. Run off of 10% of total put in. But it can take a minute to saturate and do that…but your in soil. Becareful watering in soil***


Ok so if I put in a quart and more than 10 percent comes out that means I did too much, and should test some other time after it dries out a bit?

And if less comes out I should add a bit more water?


Soil does not hold air when saturated. I see thats fast draining media. When you fo full soil do not saturate the plant because the roots can drown and thats a dead plant.


These are canvas 5 gal bags and I added quite a bit of perlite to that. And it’s 105 outside so I think we good on that.


Yes basically. Runoff is tricky especially if your newer to growing! I think it matters more after the first 2 weeks. … But thats why your here to get some help. We will help you out no problem.


Oof 105 damn yea they’ll transpire that fast. Im having trouble staying under 91 inside. Need ac in the grow but ive been able to get away without it for 4yrs.


If your plants are healthy then don’t worry it so much. Remember most of checking the runoff we are trying to see how much nutrients are in a inert medium like coco or Promix which are devoid of nutrhents, the pre-mixed soils have amendments added in, either organic or chemical to give you nutrients for the first few weeks of your grow. It isn’t just nutrients that will up your PPM in your runoff, it also includes things like humic acid, and just plain ol particles that will conduct electricity in the water. So if they are healthy, and growing good, just don’t add more nutes, it won’t make them grow faster unless they are lacking them. If you go too much it is worse thn not enough.



Yep theres a lot of stuff in premixed soils. Its kind of a learn as you go really. Take notes and less is more. If you change small things and record it in your notes its easier to figure out where you went wrong. And really we need some pics of the plant. And some more info on your grow. A support ticket helps us identify issues you may not be aware of.


Support ticket ](Support ticket)

Feb '21

Hello and welcome to the Growers Network Family. We are very glad you are here with us now. You couldn’t come at a better time than now! Lol. The community will help you out, if you so desire any assistance.

To start a thread, click the bar “New Topic”

•Starting with a support ticket will help

Grow Journal Check List

Strain (bagseed too):
Indoor, outdoor:
Tent, Room Size:
Light height:
Temps (day and night):
Relative Humidity (day and night) :
Added Air (fans, portable acs, heaters, dehumidifiers) :
Pot sizes:
Soil, Coco, or Dwc:
Nutrient type:
Ph numbers:
Ec and PPM:
Water Temps:

Seed germination date:
Veg duration:
Nutrient cycles.
Slymer made this and it helps a lot!


You said it right there. In soil you don’t check ppm. There’s a ton of other stuff comes out of it. If your pH is right don’t worry about anything until they look like they’re hungry.

There’s really no way for us to help you without a picture of your plant to agree with you or disagree with you as far as the health of the plant. So I’m gonna take your word for it.

:thinking:… The old passage “ if it ain’t broke“ comes to mind. :+1:t3::v:t3:


Thanks for the advice everyone. There are 3 all planted on same day:

I may have answered my own question I thought I used starter soil, but it turns out I used this instead. (I added quite a bit more perlite):


I like them


I use the same soil. You won’t have to use nutrients for 3 to 4 weeks, just pH your water!