Look at the line for 1.0 E.C.
that is the conversion factor for each brand.
Look at the literature that came with your meter.
What conversion factor does it use?

i looked on the box and in the instruction manual but do not see anything about conversion factor

i found it.

it says for model 204 (my model)

1000us/cm = 1mS

what does that mean?

i sent an email to the manufacturer asking if their ppm reading was x500 or x700 and this is the reply i got....

The ppm reading is just what it says on the meter. So if it read 1200 your ppm is 1200 ppm. Please remember the RM frequencies can have an effect on meters. So keep digital or electronic ballasts away from meter or use a ground fault plug. Same you would use for computers.

now im even more confused.

Use your calibration liquid to determine conversion rate. Firstly calibrate to 1000 ppm (as it says) then switch from PPM to EC conversion and read the EC while dipping in 1000 ppm solution. And there you have your conversion rate the instrument uses.

PS: when saying "switch from ppm to EC conversion" it's technically not correct. It should say "switch from PPM conversion to original EC. Anyway, - calibrate to 1000 ppm and switch to EC reading and measure what the 1000 ppm liquid reads in EC.

Be aware that the shown ppm are no elemental PPM of your nutrients, but an inaccurate conversion rate that doesn't exactly correspond (as it can't respect your components in the solution) but gives only "something close but far from exact"! No matter what the manual says ;-)

i dont have 1000ppm calibration solution. i was given 2760 buffer and i calibrated for to that.

the tri-meter cannot switch back and forth between PPM and EC. they have a model that reads in EC and a model that reads in PPM. mine is PPM only.

PPM only is worthless for my understanding - and if they don't tell what conversion rate they actually use in the first place,- that's kinda pathetic.

Well, you've bought that breading dog with one testicle now...
If you don't find it in the manual or by asking them, you can make your own "conversion solution": 2 gr calcium nitrate dissolved in 1 liter of water should read 2.0 mS/cm. Not accurately, as the exact reading will depend on- and vary with purity. But this is good and accurate enough, to deduce the conversion rate of your instrument.

You might not have any calcium mitrate handy after all...
Here you go even simpler:

Dissolve 2 gr of pure table salt in 1 Liter of (distilled) water. If your Instrument measures around 2000 ppm at 25°C, the conversation rate is 500.

Hey chinamon, the conversion rate for your model(204) is 700. I have the 202 model and my conversion rate is 500. Go by the Truncheon levels on the graph.

To do the math, you will take your ppm, say 840, and divide it by 700. That will give you a EC of 1.2.

urbangardenfarmer,

THANK YOU! i kind of had a feeling it would be x700 but i wanted to be sure.

weird, capsicum ppm should be 1260-1540. when i mix my DNF nutrients according to the label on the bottle it takes me to over 2000ppm. i only have to use about half strength which also saves me money! woot! (my tap water is about 420ppm)

Am I truly the only person here who can see the REAL paradox with buying a so called TDS-meter that converts to a "fictional" ppm content of the actual nutrient?

While a more common conversion rate of 1.0 mS/cm to 500 ppm is some 15-20% off the actual ppm content of a common nutrient solution, a conversion rate of 1:700 is just completely off the real thing.

First of all the information "capsicum ppm should be 1260-1540" is just an abstract, without giving either the conversion rate- 500/700 or stating that it is the amount of actual elemental ppm, which indeed is a very different thing on top of it.

You should always using (well I believe that's what everyone is aiming for) the proper and balanced amount of nutrients, not some non-defined number that varies with conversation rate, right?

Imagine farmers in Western Europe, the Ukraine and India, using different weight units. While the Europeans have 1000 milligram per gram, the Ukrainians' unit, when converted is only 700 milligram per gram, the Indians use a unit that converts as little as 500 milligram per gram. Now there will be a worldwide recommendation for the use of Nitrogen for peppers that says 10 gram per square foot. So, will the Europeans be the wasteful, the Ukrainians perhaps getting it right and the Indians saving millions? Nahhh....

Simply take your tap water, you say IT IS ABOUT 420ppm. Well IT IS NOT, only your instrument measures and says falsely 420ppm. Get a official or lab analyses of the same water and it will, as sure as I sit on my bottom right now, NOT tell 420 ppm. Measure it with a Hanna conversion rate it would be only 300, - but how much "dissolved solids in ppm" has it for real, how much ppm are there actually in that tap water?! The truth is that neither a EC-meter, nor a 500 conversion or a 700 ppm conversion instrument can measure it. Only a dehydration can tell the total dissolved solids, and only a analyses can tell how much ppm of each component there is. The very same thing applies to your or any other nutrient solution.

As long as we don't talk (and actually measure) EC and mS/cm for a nutrient solution, and use PPM ONLY for the elemental/actual content of each of the Macro- and Micro nutrients (as in N= 150ppm, P= 35ppm), - there will always be confusion and ERROR!

ok i just got an email back from the actual manufacturer. the last email i got back was from a distributer i think. the 204 model which i have reads in EC. if it reads 1000 then its 1.0 EC. if it reads 1680 then it is 1.68 (almost 1.7) EC. whew!

In that case you would have got your very unique and own conversation rate. That is something LOL. Have you checked (compared) what they say (pretend) with the chart? What do you conclude from that about your actual conversion rate?

My bad chinimon. I was giving second hand advise, which obviously was incorrect. I'd say the manufacturer knows best.That makes me wonder if my 202 model is incorrect? Could you send me the manufacturers email, so I can double check? You would think this would be written clearly on their website!?

urbangardenfarmer,

here is what the email said. it should answer your question

Hi Jason,
We manufacture 3 models on our nutradip trimeter. The 204 model that you purchased reads in EC not ppm . Our model 202 ppm reading is .5 of the to EC reading and model 203 ppm reading is .7 of the EC reading.
So for example if the EC reading was 2000 EC the .5 conversion meter (model 202) the ppm reading would be 1000 ppm. If we were using the .7 conversion meter (model 203) an EC reading of 2000 EC would be 1400 ppm.
Hope this helps. Any question or concerns just email.
Cheers,
Barry Stonehouse
Future Harvest Development

Nevermind, just found it.

The three different Nutradip Tri-Meter Models differ in the way each display microsiemens, as indicated below:

202 - converts microsiemen to PPM factor (0.5)X(microsiemen)
203 - converts microsiemen to PPM (for fish) (0.675)X(microsiemen)
204 - is microsiemen factor (1.0)X(microsiemen)
A calibration solution set to 1000 microsiemen would require that you calibrate each model as follows:

Model 202 - 100
Model 203 - 135
Model 204 - 200

Sorry for the giant pic :~) BTW lucas, this is the reference solution I'm using to calibrate. Just to double check, do I multiply 0.5 x 2930= 1,465 to find my calibrating ppm?

the store i go to gave me a bottle of EC 2760 MMHO Buffer. i asked the barry from Future Harvest Development if i was using the right stuff and he said yes. im happy. :)

@ urbangardenfarmer,

>>BTW lucas, this is the reference solution I'm using to calibrate. Just to double check, do I multiply 0.5 x 2930= 1,465 to find my calibrating ppm?Yours is in fact supposed to be the 1st (on the bottle). Yours is the NaCL scale (500) and in the case of this solution 1500. Here again it's getting confusing, as millisimens is in fact very close to the actual ppm of NaCl, but only close, as in 3.0 millisimens equal 1,465 ppm instead of 1,500. That's why they got the "bright" idea to converted to 500 ppm for 1 millisimens in the first place.

About the info in the email: it looks correct and plausible - so chinamon then actually got an EC meter in microsimens and hence doesn't need to convert to them.

For those who didn't realize it: 0.5 (.5) microsimens per centimeter (µS/cm) equals 500 millisimens per centimeter (mS/cm) and obviously 1.0 mS/cm equals 1000 µS/cm. No conversion needed, the 204 is in fact an EC-meter!

PS: I should give an example some day (in a separate post) to illustrate what I explained earlier about actual ppm in a nutrient solution and the ones a "TDS-meter" will/can read - respectively why both are a different pair of boots and do not correspond.

I also want to say that it actually took me a LONG time to truly figure it all out and that I had a few misconceptions about it myself - as it truly is CONFUSING like HELL for everyone ... ;-)