Can EC be converted to elemental ppm?
- Thread starter Flowki
- Start date
Calculating PPM from EC is just a ballpark. The TDS meter measures the conductivity of your water, and reports what the PPM would be if you were measuring a solution of either NaCl (500 scale) or KCl (700 scale). So your meter isn't going to be accurate for PPM unless you're feeding your plants table salt in distilled water.
Normally you're just using your EC meter to detect change. You know the amounts of NPK when you mix your reservoir (let's pretend that labels are always accurate) and measure your EC. The trend next time you measure lets you know what the plant is doing, and what to add to restore the reservoir to what it was when you mixed it.
It's good to be aware of elemental PPM when you're reading lab reports, but almost everyone online is working in K2O and P2O5. At least I think they are. Someone please tell me if they aren't, hah.
Normally you're just using your EC meter to detect change. You know the amounts of NPK when you mix your reservoir (let's pretend that labels are always accurate) and measure your EC. The trend next time you measure lets you know what the plant is doing, and what to add to restore the reservoir to what it was when you mixed it.
It's good to be aware of elemental PPM when you're reading lab reports, but almost everyone online is working in K2O and P2O5. At least I think they are. Someone please tell me if they aren't, hah.
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Flowki
Well-Known Member
That's really the problem I am facing, I worked out the ele ppm of dry salts, but nobody else is talking in terms of ele ppm. That's obviously my own fault. I just rather work out what's going in, than constantly depending on meters that can drift or give wrong readings depending on temps. I know meters are suppose to compensate for that, but again, more things to go wrong imo.
N 64 + 75 = 139
P 63 + 22 = 85
K 90 + 29 = 120
C 95
M 30 + 25 = 55
S = 32
The overall max ele ppm at any time, including micro nutrients does not exceed 600 elemental ppm (as far as I am aware). I am attempting to use blumats again with no run off so trying to get a base line of what other people use in similar situations. One guy I found is doing insanely good with timer feeding and no run off, he estimates his EC is between 1.4 to 1.6.
My base is 1.2 ec at 1g/l, according to the manufacturer (gotta trust something). 0.5 gpl of cal nitrate and 0.25 gpl of mag sulph, along with 0.10gpl of mkp, is probably pushing over 1.6 ec, but I just want to know where it's at.
N and C are reduced as P and K are increased in mid flower, so realistically the ppm is going to be closer to 520, if the above calculations are correct. I'm just wanting a rough idea so that I know I am safely within range, and to double check I didn't mess any calculations up. S is low by what I've read, 60 ppm is the better spot, but that's another thing.
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twentyeight.threefive
Well-Known Member
Just buy an EC meter, it's not that hard. Like $15 on Amazon.
Flowki
Well-Known Member
If I ask somebody how much of a given element they are using, they rarely know, since they are speaking only in vague EC terms, or ''1/4 recommended of X product''. Most of us are using various products with differing ratios. X ec or 1/4 strength is not a good answer to ''how much N are you using at X stage''. Most of the advice given on nutrients would only be of real use if you are using the exact or extremely similar products as the person giving the advice.
Flowki
Well-Known Member
Ah cheers I will take a look. Is that conversion an estimate to elemental ppm?. That's the only one I have calculated with, it's free and universal, I just figured more people were using it because of that, obviously not.
I'm running blumats again so I want to try and get near the lower end of feeding just enough. I don't know if the blumats will be too small, or some personal error in set-up, so I am concerned that the lower portion or outer edges of pots may dry out. If that happens, I want as little salt in there as possible, so that the damage is hopefully limited. I've seen the damage it can do, personally and with other people. I also find it useful to ask somebody say how much N they use at X time, and to have a universal answer, rather than ''1/4 cal mag''. I don't use calmag. For example I've asked people using blumats with good results, what they are using, and they don't really know, just X amount of X product. I'd have to ask every single product they use, how much, when, and then convert it all. Starting to wish I just payed more for the ease of commercial products.
J232
Well-Known Member
Best bet is to read threw the site, start with this fuckers post. Check out the calculator.
Understanding and Calculating Nutrient PPM
Understanding and Calculating Nutrient PPM PPM (Parts Per Million) can seem like a mystery but it’s actually very simple. Basically the idea is to quantify how much “stuff” is in your water. PPM is commonly measured by a grower using an electronic pen which measures the electrical conductivity...
www.rollitup.org
Flowki
Well-Known Member
Will do, cheers
Yup that's it.