Ppm, tds? Wtf?

dksmska

Member
I truly do not understand! I have read the forums and several posts. Read the conversion charts, and looked it up on line! We have a ph meter, ok, good. We also have a ppm, ec, tds meter, however the ec reading is nowhere to be found! The ppm is running around a thousand, but the tds is running around 2000. It is a hanna meter. So what is my actual ppm? Is it the ppm, or the ppm x .50, or is the ppm the tds? WTF? Anyone???????
 

m420p

Well-Known Member
TDS stands for Total desolved solids. PPM is parts per million which is a measurement of the total dissolved solids in your nutrients solution (you pry already knew this). Idk what your talking about with the meter, do you have a online link to the meter you bought or a pic. What do you mean EC reading is nowhere?
 
A TDS meter is really just an electrical conductivity (EC) meter that has a built-in conversion factor that displays the output in parts per million (ppm) of total dissolved solids (TDS). EC is displayed in µS/cm (but not always) The trouble is that the relationship between the conductivity of a solution and its content varies not only by the concentration of the dissolved ions, but is also based upon the charge and mobility of the dissolved ionic species.​
As a very simplified explanation of that, imagine a small ion and a large ion having the same electrical charge. The small ion will find it easier to move in the solution, so "conducts" that charge faster, so gives a higher EC for the same concentration (TDS) in the solution. Likewise, if two ions have the same size, but one has a higher charge than the other, it too will show a higher EC.
I really only use EC as my measurement reading as the others are just calculations based off EC. Not sure about Hanna, but your EC should be a number like 1.0 or 1.5 etc.




 

m420p

Well-Known Member
It might not say "EC". It might just give a reading in microsiemens/cm or ms/cm which is measurement of EC. I only use EC.
Heres a chart that may help.
 

don2009

Well-Known Member
A TDS meter is really just an electrical conductivity (EC) meter that has a built-in conversion factor that displays the output in parts per million (ppm) of total dissolved solids (TDS). EC is displayed in µS/cm (but not always) The trouble is that the relationship between the conductivity of a solution and its content varies not only by the concentration of the dissolved ions, but is also based upon the charge and mobility of the dissolved ionic species.
As a very simplified explanation of that, imagine a small ion and a large ion having the same electrical charge. The small ion will find it easier to move in the solution, so "conducts" that charge faster, so gives a higher EC for the same concentration (TDS) in the solution. Likewise, if two ions have the same size, but one has a higher charge than the other, it too will show a higher EC.
I really only use EC as my measurement reading as the others are just calculations based off EC. Not sure about Hanna, but your EC should be a number like 1.0 or 1.5 etc.




WTF! You just made it worse!
 

don2009

Well-Known Member
TDS stands for Total desolved solids. PPM is parts per million which is a measurement of the total dissolved solids in your nutrients solution (you pry already knew this). Idk what your talking about with the meter, do you have a online link to the meter you bought or a pic. What do you mean EC reading is nowhere?
Great answer keep it simple and smart!
 

dksmska

Member
I mean the damn meter gives us a reading for ppm and tds but not ec. Also gives water temp. No the chart does not freaking help, but thank you! Read that there is a conversion factor so that even if your ppm says 1000 it's really like 1400, but also read that the tds is the ppm! WTF? What number should I be using?
 
Being that TDS is measured in ppm, would the "other" number not be the EC? it seems it may just be in ms/cm not micro/cm. So the EC in this case would be like 1000 measured as micro/cm or 1.0 as ms/cm
 

dksmska

Member
No decimals anywhere in the readings! Looking for the damn box, had it next to the computer the other day to look it up on the damn hanna website! Just confused me more! Frustrating, i'm usually a quick learner! Don't mind poking around here to find answers, but this shit is confusing!!!!!!!!
 
there won't be decimals if it is measured in micro/cm.

EC of 1000 measured in micro/cm is the same as EC of 1.0 measured as ms/cm
 

dksmska

Member
Still confused, trying to comprehend, but should I be reading the ppm or the other number? Is ppm the ppm on the chart or is it the other number on the freaking meter? If the nutrient chart says to be at say 1100 ppm, why does that not seem to have anything to do with what the freaking meter says? Why are there two different readings? As I said before, WTF?????
 

m420p

Well-Known Member
whats the difference of both readings. ex. one says 500 ppm, the other says _____

Id still like to know exactly what meter your using.
 

m420p

Well-Known Member
The other number is most likely EC in microS/cm although 2200 is a tad high for 1000 ppm, you can compare on the charts I provided earlier. it would be 2.2 in milliS/cm(move decimal) on the big chart.
 

m420p

Well-Known Member
What nutrient/grow chart are you using? I use EC so I basically use the chart I provided earlier with this one:

PPM for Hanna Chart PPM

Seedlings, Early Sprouts 100 to 250

Early Vegging 300 to 400

Full Vegetation 450 to 700

Early Blooming 750 to 950

Full Mature Blooms 1000 to 1600
 
Top