Did you know that if you use advanced nutrients a ec/tds pen will not read accurately? I asked them and they said it is not a good way to get an accurate ppm or ec reading because of humic acids and other things that are in it that contribute to a higher ec/tds without being nutrients themselves
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An EC pen measures the electrical conductivity of a solution. Different ions within the solution will contribute to the conductivity including ions that are not taken up by the plant.
EC meters/pens are calibrated to a solution of NaCl or KCL. A certain amount of such substances act as the baseline and will read with high accuracy only with NaCl or KCL. For other of substances, the ions will also contribute to the conductivity but it’s more of a close estimate.
For something such as large molecule organics which are not really directly up taken by the root, the solution conductivity is also affected but the results may be misleading relative to a strictly salt based solution.
For the all-in-one formulas, you’d probably need to get the target EC from the vendor. For salt based formulas where you amend other substances such as organic acids, you could measure the EC prior to the amendments. The amendments will probably contribute to some extent additional minerals but the bulk (e.g. large molecule organic acids) will likely not be up taken by the roots.
Many times I run salts + amendments in a peat/coco substrate. My target EC is for the salts. Then I amend with amino acids, carbohydrates/sugars, myco, and other things on a rotating basis. The end EC results will vary depending on the amendments but the salt EC (immediately available) is consistent.
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Yeah so it isn’t actually accurate, like some would assume. It’s more of a baseline because say if you know its hypothetically a 1.0 ec and you realize you were too strong because of a plants reaction then to go down to say a 0.7 ec may not be the correct numbers but can still help in those ways is my take on using it with other things that will add to its results
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The numbers mean very little to me im more just watching for trends when I check.
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Yes. Accurate but misleading. It’s simply electrical conductivity and anything that will disassociate in a solvent (water) are generally ions that may contribute to the EC. Whether it’s available to the plant or not.
Things becomes more relative with organics in the mix. The movement of the PH / EC should still provide some insight as to what the plant is up to depending on the growing style. Same with making adjustments. The numbers may not match up with someone running pure salts or such.
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Agreed, that’s pretty much how I intend to use it, like you and Neb said… it’s better for those purposes
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Not everything is dissolved. Not everything is a solid.
For NPK in RO no ppm pen should be used.
PPM= %NPK × grams/ml / Liter X 1000.
So 202020 is 60 so 1g of it in 1 L is .6k ppm or 200 200 200ppm.
AN contains ingredients many have found and done DIY
Heres megacrop example feed
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Right i.e at high ppm mine is pretty off for potassium citrate for example a low salt index K feed
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