Dr Who is right! ... Rx Green Technologies Report

twentyeight.threefive · Jul 7, 2022

rkymtnman said:
correct. so a tds meter is not the same as an EC meter. thanks. a siemen and parts per million aren't the same either.

for further arguments: call these people and argue with them. this is just one source that says the same thing.
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ref: 06 Oct 2020 article

BTW I’m not arguing with you. I’m pointing out that you are wrong and I’m explaining to you why.

rkymtnman · Jul 7, 2022

twentyeight.threefive said:
It’s exactly the same. They both measure EC….

maybe i'm reading that paragraph wrong then. an ec meter measures electrical conductivity, a tds meter is only an estimate of electrical conductivity.

is that the same? i don't think so. if you think those are the same, that's fine with me

PJ Diaz · Jul 7, 2022

rkymtnman said:
maybe i'm reading that paragraph wrong then. an ec meter measures electrical conductivity, a tds meter is only an estimate of electrical conductivity.

is that the same? i don't think so. if you think those are the same, that's fine with me

It's saying that the TDS meter also measures electrical conductivity, and then uses a conversion factor from that to estimate TDS.

rkymtnman · Jul 7, 2022

twentyeight.threefive said:
BTW I’m not arguing with you. I’m pointing out that you are wrong and I’m explaining to you why.

that's cool. i don't see how you think a meaurement and an estimate are the same thing.

twentyeight.threefive · Jul 7, 2022

rkymtnman said:
maybe i'm reading that paragraph wrong then. an ec meter measures electrical conductivity, a tds meter is only an estimate of electrical conductivity.

is that the same? i don't think so. if you think those are the same, that's fine with me

No you’re reading it wrong. A EC meter measures and displays EC.

A TDS meter reads EC and displays ppm calculated from the EC reading times a scale. If it’s a 500 ppm scale TDS meter and the pen reads 1 EC then the display shows 500 ppm.

rkymtnman · Jul 7, 2022

PJ Diaz said:
It's saying that the TDS meter also measures electrical conductivity, and then uses a conversion factor from that to estimate TDS.

see post 204. so you think an estimate is the same thing as a measuremetn too? that's cool too.

rkymtnman · Jul 7, 2022

twentyeight.threefive said:
No you’re reading it wrong. A EC meter measures and displays EC.

A TDS meter reads EC and displays estimated ppm calculated from the EC reading times a scale. If it’s a 500 ppm scale TDS meter and the pen reads 1 EC then the display shows 500 ppm.

fify

twentyeight.threefive · Jul 7, 2022

rkymtnman said:
fify

Correct TDS pens estimate ppm from the EC readings they measure.

I though we were clear on this? You can’t measure true ppm without knowing either both volumes or masses.

I also never said an estimate was the same as a measurement.

PJ Diaz · Jul 7, 2022

Bro, look at what you posted yourself:

rkymtnman said:
In summary, there is a correlation between conductivity and TDS. They are not the same. TDS meters that use conductivity to generate measurements only estimate TDS

PJ Diaz · Jul 7, 2022

If you see two little metal probes coming out of your ppm meter, it's measuring conductivity. It's basically a tiny preset resistance meter. Nothing fancy. It sends an electrical DC impulse out, and measures the resistance between the probes.

rkymtnman · Jul 7, 2022

twentyeight.threefive said:
You can’t measure true ppm without knowing either both volumes or masses

agreed.

i've changed my mind so i'm agreeing with you both now, an estimate from a tds meter is the same as an actual measurement from an ec meter.

see that was easy, huh?

Billy the Mountain · Jul 7, 2022

rkymtnman said:
sorry but that's not correct from what i've found

So, what is the difference between conductivity and TDS meters?
In pure scientific terms, conductivity tells you how well electricity is passing through a substance. On the other hand, TDS indicates the amount of dissolved solids within a liquid, accounting for both conductible and non-conductible particles.
In practice, when measuring conductivity and TDS both conductivity meters and TDS meters pass electricity through a liquid. In fact, conductivity meters are used to estimate the TDS in a substance.
How is this done? Simply, TDS meters measure conductivity, then apply a conversion factor. Even if your meter is a TDS-only meter and does not display conductivity it still uses electrical conductivity with a conversion factor to calculate the TDS results.
Why? Well, for a true TDS measurement you have to evaporate all the moisture from your sample, then weigh the solid residue. While this is the most accurate method, in practice it is often impractical.
In summary, there is a correlation between conductivity and TDS. They are not the same. TDS meters that use conductivity to generate measurements only estimate TDS

if they measure in 2 different units (siemens and parts per million) , they can't be the same thing. one is an estimation of the other.

I don't now where you read that a tds meter measures anything but conductivity, please share.
They both measure conductivity, and only conductivity.
The ONLY difference is the displayed value to approximate the ppm of a reference salt; in the case of TDS, 500ppm NaCl = 1.0 EC

rkymtnman · Jul 7, 2022

Billy the Mountain said:
I don't now where you read that a tds meter measures anything but conductivity, please share.
They both measure conductivity, and only conductivity.
The ONLY difference is the displayed value to approximate the ppm of a reference salt; in the case of TDS, 500ppm NaCl = 1.0 EC

maybe i'm being too strict then with my definition of not being the same thing?

i think meter 1 that measures ec directly and displays that in mS is not the same thing as meter 2 that measures ec and then estimates a value of parts per million via 3 different conversion factors (0.5 , 0.7 and 0.64) and displays ppms.

anyway, that's my last post on this subject. if meter 2 converts and approximates, then it can't be the same thing as meter 1 that does neither. nobody will convince me otherwise.

Billy the Mountain · Jul 7, 2022

rkymtnman said:
maybe i'm being too strict then with my definition of not being the same thing?

i think meter 1 that measures ec directly and displays that in mS is not the same thing as meter 2 that measures ec and then estimates a value of parts per million via 3 different conversion factors (0.5 , 0.7 and 0.64) and displays ppms.

anyway, that's my last post on this subject. if meter 2 converts and approximates, then it can't be the same thing as meter 1 that does neither. nobody will convince me otherwise.

Focus on the aspect that both meter1 and meter2 measure the exact same thing: conductivity.
The only difference is how they display that measured conductivity

twentyeight.threefive · Jul 7, 2022

rkymtnman said:
maybe i'm being too strict then with my definition of not being the same thing?

i think meter 1 that measures ec directly and displays that in mS is not the same thing as meter 2 that measures ec and then estimates a value of parts per million via 3 different conversion factors (0.5 , 0.7 and 0.64) and displays ppms.

anyway, that's my last post on this subject. if meter 2 converts and approximates, then it can't be the same thing as meter 1 that does neither. nobody will convince me otherwise.

Wait. Wait about my meter that displays EC AND ppm? It’s not the same meter?

waterproof808 · Jul 7, 2022

This is one more reason everyone should only use EC instead of PPM's.

Bucsfan80 · Jul 7, 2022

PJ Diaz said:
It's saying that the TDS meter also measures electrical conductivity, and then uses a conversion factor from that to estimate TDS.

An estimate is pretty much a guess so in other words they guess the ppm from the EC

Bucsfan80 · Jul 7, 2022

twentyeight.threefive said:
Wait. Wait about my meter that displays EC AND ppm? It’s not the same meter?

View attachment 5159823

Same meter just with a correct conductivity value and an estimated ppm value

Billy the Mountain · Jul 7, 2022

Bucsfan80 said:
An estimate is pretty much a guess so in other words they guess the ppm from the EC

And a wild guess at that, unless your measuring table salt with a TDS meter

The displayed ppm value is only valid for the salt for which it's calibrated and nothing to do with the elemental ppm of a nutrient solution with various salts present.

For example, my current hot pepper feed of Maxi Gro/Bloom is 2.0 EC but the total elemental ppm is 663, a TDS meter would display 1000ppm

PJ Diaz · Jul 7, 2022

Bucsfan80 said:
An estimate is pretty much a guess so in other words they guess the ppm from the EC

It's a conversion factor, so it will be consistant in correlation to EC, whereas a guess would be inconsistant.

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