Help me understand the math

I am using FFOF soil. I purchased a Blue Lab PPM meter and it is calibrated for EC. Because I purchased the PPM meter and I am not completely sure how to use it I decided to try it out using the slurry method of one part soil to two parts water. The soil sample was taken from the lower middle of the pot. I used purified RO water. Prior to creating the slurry the readings for the water was EC 0.0 and pH 8.0. After the water was added to the soil and mixed it sat for 40 minutes. The readings of the slurry sample were EC .05 and pH 6.3. Could someone tell me what that means in terms of adding nutrients using the FF Trio or just needing to use plain water with no nutrients added? Having read elsewhere I understand the readings may sometimes vary to the point of uncertainty. So, I really don’t know what I am looking at here…feedback?

Ec multiply by 1000 divide by 2 so you’re at 250 which seems low for ffof but thinking about it I don’t think slurry tests are the best for ppm you re better off getting running off for ppm

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We really shouldn’t care about EC or PPM when using soil. Instead, relying on soil analysis (before or after a grow) and amending for tomatoes or hemp.

A detailed soil analysis will reveal actual nutrient composition. They’ll tell you how to amend the soil.

EC tells you the concentration of salts in a liquid. It’s critical to understand the salt concentration in a soilless or hydroponic grow because if they’re too concentrated your plant can’t uptake water and if they’re too low your plant will be deficient.

In soil, nutrients are delivered to the plant through cation exchange, not water. The nutrients don’t necessarily need to be plant available if you have a good rhizosphere full of microbial life.


Thank you! I’d give you a like but I “have to wait ten hours.” (I think that means I’m supposed to go to bed.) Your information was quite informative. I looked up a few of the words you used to educate myself further. I have a better understanding of EC, soil environment, and some of the nutrient process…Thank you!

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Thank you! What I have read elsewhere confirms what you have indicated; that slurry tests are not the best for these readings.

That’s true I didn’t take a single ppm test in my organic grow because A I couldn’t do anything about it without ruining my microbe ecosystem and B Its slow release(through breakdown) so it wouldn’t be that accurate of nutrients in the medium anyways

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