Hanna TDS meter calibration questions

slimm

Well-Known Member
There are different calibration solutions for these Hanna EC/TDS meters. It seems confusing to me that there are different calibration standards (1382, 1500, etc.).

Is there one standard that is recommended?
If not and people do not use the same standard then how can we make sense out of the ppm values people talk about?
Three different people measuring the same reservoir will come up with different ppm numbers depending on the calibration standard they used to calibrate their meter. Can anyone help a new hydro grower make sense of this?
 
I might be wrong, its Friday, and I am getting FRIED,
but
the way I did it,

you adjust the meter to equal the calibration solution. The solution can be 1000, or
500, it doesn't matter. You wnat the meter to equalt he solution and then you know the meter is correct.

Your reasoning is not right.
 
Ok so suppose you and I both calibrate our meters. You use the 1382 calibration solution and I choose the 1500. What would you expect if we both measure the same 1000ppm sample? What will each or our meters read? I am under the assumption that they will read differently as they have been calibrated to different standards. Please correct my understanding.
 
You calibrate your meter to 1500. It reads 1500 when put in something with a ppm of 1500. Then you stick it in something with a ppm of 1000, it will read 1000 because it was adjusted to be accurate. I calibrate mine to 1382, and stick it in something else with a ppm of 1382, and it reas 1382. Then I stick it in something that is a ppm of 1000 and it will read 1000. Both of our meters have been calibrated to an accuracy so when put in a different ppm, it will read it accurately.

Your thinking and reasonig is off.
 
...

Your thinking and reasonig is off.

I don't have a full picture of how this works in my head so I agree my reasoning could be off. However let's discuss how these things work before jumping to conclusions. I don't think the questions in the op have been answered.

I may have part of the answer though. What I learned is that one must use the calibration solution matched to the conversion factor of their meter. It turns out that some meters have a hard coded conversion factor and others, like my Hanna, have a programmable conversion factor. I have mine programmed to a conversion factor of 0.7.

A meter with a conversion factor of 0.7 must use the 1500 ppm calibration solution to get a true reading. If you had the same meter as me, programmed to a 0.7 conversion factor just like me, but calibrated using the 1382 calibration solution and we both tested the same 1000 ppm sample we would end up reading different results on our respective meters. But if you reprogram the conversion factor of your meter to match your 1382 calibration solution then you and I will agree on the TDS of the 1000 ppm sample.

Does this seem correct or am I still missing something?
 
oh and yes you did crack the whole (conversion factor) bullcrap that hanna pens feature. they're nice though, and easy to use once you calibrate it properly.
 
PPM-EC-C.jpg
 
Thanks Roseman. I have seen that chart before and it never meant much to me when before I got involved in hydro.

This chart reminds me that I bought the Hanna meter at a local shop and it was set for the 0.5 conversion factor. The salesman told me that, locally, most people use the 0.7 conversion factor so we programmed the conversion factor to 0.7 and calibrated the meter with 1500 ppm solution.

I am partial to the EC measurements over ppm - it somehow seems simpler to talk about 1.9 rather than 1450 ppm, etc. It seems that the EC scale is more widely used in Europe than it is in the US.

My questions about calibration and the need for different calibration solutions have been answered. Thanks everyone.
 
and what is this telling us?

It shows that there are different scales to measure the dissolved solids in solution. Unless I am still confused this means that, when given ppm numbers by another grower, one must know what scale they are reporting them in for them to be meaningful.
 
Now I am curious what scale most of our 420 members are using. Perhaps a poll is in order...
 
It shows that there are different scales to measure the dissolved solids in solution. Unless I am still confused this means that, when given ppm numbers by another grower, one must know what scale they are reporting them in for them to be meaningful.

that can't be right. if a solution has 1000 ppm of tds, what use would a meter be if it did not tell you that it has 1000 ppm? the solution is what it is, it's only a question of correct calibration of your meter.
 
that can't be right. if a solution has 1000 ppm of tds, what use would a meter be if it did not tell you that it has 1000 ppm? the solution is what it is, it's only a question of correct calibration of your meter.

1000 ppm solution as reported in the Hanna, Eutech or Truncheon scale?
 
dude, ppm is a numerical count of the total dissolved solids, period. its not about different scales or anything else. its about correctly calibrating your meter to give an accurate reading of the tds count. period.
 
dude, ppm is a numerical count of the total dissolved solids, period. its not about different scales or anything else. its about correctly calibrating your meter to give an accurate reading of the tds count. period.

I really think you should reconsider Hogdady.

Total dissolved solids (which are expressed in ppm) is not measured by these TDS meters. In fact they cannot measure TDS; all the meters can measure is Electrical Conductivity (EC) and use that to derive an approximated TDS ppm value. As manufacturers created these gadgets they failed to compare notes, and the methods they use to do this calculation do not all agree. Today, with meters like mine, you can simulate any one of the other meter standards by making an adjustment to the conversion factor. There are three conversion factors which various manufacturers use for displaying ppm's...

USA 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
European 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
Australian 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

When I went to buy my meter I had no idea that the measurement industry was so fragmented or I would have researched it more before I selected a meter. Not that I necessarily would have chosen a different one. Mine has a programmable conversion factor so I think I'm ok. I started this thread because I read a lot of on-line growing information and everyone is talking about the ppm of their solution. I would like to know - which scale should I use and how do I express / interpret TDS values when discussing with others?
 
Hogdady. From what I understand there is a true dissolved solids measurement that is absolute like you say, but taking that the measurement is more difficult than measuring EC and approximating TDS. If you want to know the true TDS value of a solution you can use the Gravimetric methods which involve evaporating and weighing the remaining solids. There are some problems with this method too since some of the dissolved solids may be volatile enough to evaporate with the water.
 
I really think you should reconsider Hogdady.

Total dissolved solids (which are expressed in ppm) is not measured by these TDS meters. In fact they cannot measure TDS; all the meters can measure is Electrical Conductivity (EC) and use that to derive an approximated TDS ppm value. As manufacturers created these gadgets they failed to compare notes, and the methods they use to do this calculation do not all agree. Today, with meters like mine, you can simulate anyone of the other meter standards by making an adjustment to the conversion factor. There are three conversion factors which various manufacturers use for displaying ppm's...

USA 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
European 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
Australian 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

When I went to buy my meter I had no idea that the measurement industry was so fragmented or I would have researched it more before I selected a meter. Not that I necessarily would have chosen a different one. Mine has a programmable conversion factor so I think I'm ok. I started this thread because I read a lot of on-line growing information and everyone is talking about the ppm of their solution. I would like to know - which scale should I use and how do I express / interpret TDS values when discussing with others?

I entirely understand what you are saying, but you are missing my point entirely. Isn't the function of your meter to give you a reasonably accurate reading of the parts per million of total dissolved solids in whatever you are measuring? YES! That's the only reason we have the damn thing. If there are different conversion factors, blah, blah, blah, and the end result is an accurate representation of the ppm, then it's only how we get there thats up for discussion.
 
I just came across a thread on this subject at another site and the recommendation there when reporting your PPM in a thread to give the conversion factor your meter uses for example 550 PPM @.7 or give the reading in EC which is the same meter to meter.
 
I entirely understand what you are saying, but you are missing my point entirely. Isn't the function of your meter to give you a reasonably accurate reading of the parts per million of total dissolved solids in whatever you are measuring? YES! That's the only reason we have the damn thing. If there are different conversion factors, blah, blah, blah, and the end result is an accurate representation of the ppm, then it's only how we get there thats up for discussion.

Exactly, so if you are running a meter on the Hanna scale and my meter was designed to use the Truncheon scale we have to find a way to normalize our values so we are talking apples to apples. We can do that by always reporting values in EC or by somehow communicating the conversion factor of our respective meters.
 
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