Hannah PPM/EC meter

Discussion in 'Hydroponics' started by whiskeygirl, Feb 25, 2011.

  1. whiskeygirl

    whiskeygirl New Farmer

    I just bought a Hannah combo PPM/EC/PH meter (the black one). I want to start measuring my nutrients using EC. How do you use this pen for EC? It has 3 modes, PH,PPM and uS? Is this uS the same as EC? It gives you a huge number in ths mode. I thought EC should be like .2,.3.,.4...etc..

    Thanks
    WG
  2. Smokey503ski

    Smokey503ski Active Farmer

    Are you sure it is both a PPM meter and EC meter? Why are you so set on using EC compared to using PPM's?
  3. sky high

    sky high Well-Known Farmer

    There is a ppm model and an EC model with this meter. Do you have the EC model?

    I'm not all that schooled on EC....I have the ppm pen. What I see is that the ppm's are calibrated using the "microsiemens" (sp?) mode... (1413 is the solution used) but you read the meter in ppms.

    from memory..I think the 91830 model is the ppm pen...and the 91829 model is the EC pen. (could be backwards but pretty sure those are the #'s)

    hope that helps somehow

    s h
  4. Seamaiden

    Seamaiden Moderator Staff Member

    Easy peasy once you understand what the thing is telling you. That uS designation is actually microSiemens, and that's the EC reading. You have to place your own decimals, it gives the reading in whole numbers. So, for instance, let's say on the uS setting it's giving you a readout of 1510, that's an EC of 1.51.

    One of the neat things about these meters is that you can set what conversion factor you want to use for ppm readings, either .5 or .7 conversion. I chose .5 just because mentally it's easier for me.

    Lastly, it's very important to understand what the meter can NOT do for you, and that's measure ppm's or EC of organic molecules, this device only gives accurate readings for chemical salt fertilizers. That means that some things, like, say... molasses, could cause your EC to look like it's going off the charts, but in reality it's right where your plants like it.

    It's better to use EC because it's not only much more accurate, but it's just plain easier to use once you have your head wrapped around it. Also, it should be noted that ppm and TDS readings are *actually* calculations based on EC.

    Have you figured out how to calibrate the meter? Calibration on a regular basis is extremely important or the tool becomes worse than useless to you. I always calibrate pH using the two-point method, and calibrate EC using the recommended solution, which if I recall is a NaCL (sodium chloride) solution at something like 1430 EC.
    The thing with calibration is that you have to hold the left button down until it says CAL while the pen is in the mode you wish to measure, i.e. in pH mode if you wish to calibrate pH, in EC mode if you wish to calibrate EC. If you continue to hold it down it will then flash to TEMP, if I recall.
  5. SierraSkunk

    SierraSkunk Active Farmer

    Thanks seamaidan, great info. I have one of those meters somewhere. Back in the day we didnt have ec meters just ppm. So i have just stuck with what i know, ppm.

    Is there an advantage measuring with ec over ppm?
  6. Seamaiden

    Seamaiden Moderator Staff Member

    PPM is a calculation based on EC (uS--microSiemens, do I keep switching the i with the e?), and there are three or four conversion factors (math speak, don't ask me to interpret) that can be used to calculate ppm, but all are based on an initial EC reading. Therefore, after having all of this explained to me repeatedly I realized that it's true--it's not only more efficient, but just plain old more accurate, to go by EC.

    I feel it's important to reiterate that you can NOT measure organic molecules with any degree of accuracy using electrical conductivity. I have some friends who are scientists and/or trained in sciences and what I found was, in essence, accurate measurement of organic molecules in a solution can be measured, but the equipment is specific to each type of molecule and is expensive as hell, as in "professional lab" expensive. I keep seeing people talking about how they've used this or that product and it's comprised in large part of organic molecules as opposed to chemical salts, and what EC or ppm results those gave, and it's just not possible. You can measure pH, but not ppm's, because conductivity cannot be measured.

    Confused more?
  7. hiboy

    hiboy Well-Known Farmer

    Your one smart cookie seamaiden. Thanks for that info.
    Hiboy
  8. OGONLY

    OGONLY Well-Known Farmer

    I think half of the people on this site don't understand that there are 2 ppm conversions as Seamaiden said.

    I borrowed a friend's meter and compared ppm of his to what mine said. There was like a 400 ppm difference (tested like 980 on mine and 1420 on his) between the two. I figured his had to be wrong because he hadn't calibrated in a while. Turned out both were correct but set at different conversions.

    Many people post ppm numbers on here without saying which conversion they are using. I'm happy to be more educated on this subject. Now I see how some people can run 1800 ppm and not burn their girls.
  9. Seamaiden

    Seamaiden Moderator Staff Member

    That's about the best way I can think of to actually show that there's a difference. What I fail completely to understand is WHY. Parts per million should be just that. But it isn't.

    Thanks for sharing that, very helpful.
  10. TheBioMaster

    TheBioMaster New Farmer

    .5 conversion is for the USA, and .7 conversion is for Europe. Just a FYI...

    As explained, PPM and EC represent one in the same value. Its really easy....if your in the USA you take your EC and multiply .5 to get your PPM....if your in Europe you multiply by .7 to get the PPM reading......but understand that your PPM reading comes from the EC value.......
  11. qnpq

    qnpq New Farmer

    take the info from the horses mouth, Hanna

    http://www.hannainst.com/usa/knowledge.cfm

    I have the same pen 98129 and the included instructions were helpful too. But the link above will answer your question & more!