Have some questions about ppm ph nutes

Ok so I’m about to switch her to flowering but I was told I need to read the runoff? I’m using 3 fox farm liquid nutes, but do I get the ph or the ppm? If I get ppm what am I looking for? Kinda confused on what to look for lol

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You will need to monitor both pH and ec/ppm as they’re both linked. I water until I get a little runoff in the saucer and measure that. Some do slurry tests and others don’t test at all. A pH that’s out will make a normally mobile nutrient unavailable to your plant. This usually leads to growers thinking their plant is hungry and feeding more which starts a downward spiral. Hope some of this helps. You need to know that the pH values are for soil. If your in coco or hydro then these values will be lower.
Here’s a guide for what you’re looking for and when.

Here’s another chart on how to convert between the two values ec/ppm

Here’s another chart that will give you an idea of pH values



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  • What strain, Seed bank, or bag seed
  • Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
  • Vessels: Pots, Grow beds, Buckets, Troths
  • PH of Water, Solution, runoff (if Applicable)
  • PPM/TDS or EC of nutrient solution if applicable
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@Davyg the first chart with the brown color, what does 1,2 1,8. What are those numbers lol

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Buggeration, the top of the chart got clipped off for some reason. Those numbers are ec levels. Some meters measure PPM some measure ec/tds. Depending on where you are the scales used will vary. I’m sure the US uses the 500 while the EU use the 700. The conversion chart let’s you switch between the two :sunglasses:

Those are the EC number. Electrical Conductivity.
An EC of 1.8 converted to 500 ppm scale (commonly used in USA) is 900 (1.8 X 500 = 900)
From the Beginning (you are probably not old enough to know Emerson Lake & Palmer) Anyway:
Every time you water or feed your plants (this applies to soil only) you give them more than the soil can hold. Doing this generates what is called runoff. You routinely want 10 - 15% runoff. If you feed 2 liters (2000ml) to a plant, you want around 200 - 300ml of runoff. You can convert to gallons, ounces, whatever measure you are comfortable with.
You collect the runoff and measure its ph and ppm.
Ph is a measure of acidity or alkalinity. Ph reading of 7.0 = neutral. <7.0 is acid, > 7.0 alkaline.
You can see from the chart showing use of available nutrients, the sweet spot is ph of 6.0 to 7.0. I shoot for 6.5 - 6.8 in soil. The ph of my input feed is right around 6.4 - 6.5.
To measure ph you need a ph pen. I use an Apera PH20. Great pen, fast and accurate and you can certainly spend more that what the PH20 costs.
PPM stands for parts per million. That is, how much dissolved solids are in the water / runoff. RO (reverse osmosis) or distilled water will have a ppm close to zero. So do not try to measure the ppm of them. The particles of stuff in the water creates an electrical charge. A ppm meter converts this electrical charge to ppms (at least I think that is how it works). So what does ppm have to do with your plants, runoff, etc. You use ppm to monitor the condition of your soil and indirectly, how much of the available nutrients the plants are consuming (or not).
For example, lets say the ppm of my new unused soil has a ppm of 2000. I then feed my plants for the first and the ppm of the nutrient mixture is 500. And I give enough to generate runoff. I would expect the ppm of this runoff to be pretty close to 2000. It may be a little less or a little higher. If the ppm is less it means some of the nutrients stayed in the soil. If ppm higher, some of the nutrients in the mix and in the soil came out in the runoff. Over time, you monitor these numbers. Generally, over a period of time you do not want the ppm numbers to increase too much. If they do it indicates nutrients are accumulating in the soil. This can lead to various toxicities, and or lockout. Basically its bad and you want to avoid it happening.
To measure PPM you need a ppm pen / instrument. I use a BlueLab conductivity pen. It is a nice quality, fast and reliable pen.
This is a very basic primer. ILGM has more info on this on its seed website. Personally I like this article Runoff pH: Explaining the Bro Science | Curious Cultivations

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I might have misinterpreted but I think @Dell5001 put the “lol” on the end of the question because he was making fun of the 1,2 and 1,8 instead of 1.2 and 1.8. That European thing…

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Hey @Dell5001 , beardless is his incognito name, he real name is Sherlock Holmes. I was having terrible issues with my last grow feed numbers and he diagnosed it right of the bat. I was using the incorrect scale and getting goofy numbers. Listen to him, lol. :laughing: