EC, TDS, or PPM

EC, TDS, or PPM

  • EC

    Votes: 6 33.3%

  • TDS (EC x 500)

    Votes: 4 22.2%

  • PPM (EC x 700)

    Votes: 9 50.0%
  • Total voters
    18
MADnuggi

MADnuggi

Member
What about organics? I've heard/thought EC doesn't work for organic solution for some reason. Is this true, and whats the best way to check organic nute strength? ppm?
 
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berkman858

Well-Known Member
MADnuggi said:
What about organics? I've heard/thought EC doesn't work for organic solution for some reason. Is this true, and whats the best way to check organic nute strength? ppm?
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I have not heard this but I have also never grown organically so I really don't know. Hopefully someone who does can chime in.
 
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berkman858

Well-Known Member
unohu69 said:
All of these can be calibrated :

http://www.ebay.com/itm/320899721531

http://www.ebay.com/itm/221010109910

http://www.ebay.com/itm/230787764727

http://www.ebay.com/itm/270504318509

http://www.ebay.com/itm/230421836851


not trying to jack your thread really, jus figured these are valid questions along with whats preferred.
and keeping the discussion alive.
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No worries, but those pens look pretty cheap to me. You get what you pay for. You don't need the best but I don't think its wise to go with the cheapest unless you don't care about it lasting long or being accurate for its lifespan, even with calibration. If you know that going in and accept that, than I say go for the $10 pen. I will stick with my Bluelab.
 
unohu69

unohu69

Well-Known Member
yeah next on my list are the Milwaukee & HM:

http://www.ebay.com/itm/370299157140

http://www.ebay.com/itm/290387817392

http://www.ebay.com/itm/260988113986

while a little more, still very reasonable i think. And these have the bonus of being waterproof (cuz hey, sometimes they get dropped in). The only reason im ok with a cheaper version is, my buddys cheapy tds-3 worked fairly well. And as long as its close, im ok with that. Im pretty sure my plants cant read a meter. like I said. Its just for a reference point.

but i appreciate your input, and take it under advisement.
 
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berkman858

Well-Known Member
Sounds like you are under no delusions so I will let you defer to your own judgement. :eyesmoke:

You are correct, your plants can't read a meter but sometimes I don't want to wait until the plant gets burned to do something about an issue. I prefer to be proactive rather than reactive, but to each their own. At least you will have a general idea of your PPM so you should be fine.
 
forgetfulpenguin

forgetfulpenguin

Active Member
Most meters measure the Electrical Conductivity of the solution (as well as the temperature obviously) and convert to Total Dissolved Salts and/or Parts Per Million. Results will vary between meters. Whether you use a meter or just look at the plant you have to fine tune until you get good results. I'll use a TDS meter until I've got a feel for the plants' needs/growth patterns, then it's easy to spot when the girls aren't as perky as they should be and do a reservoir change. I do try very hard to make sure I mix my nutrients in the same ratio and concentration after I find a mix that works. My graduated cylinders and pipettes are the cleanest things I own (I even rinse with the solution before use.)

http://www.firstrays.com/tds_and_ec.htm
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). 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.

A commercial fertilizer can be made up of dozens of different chemicals, each of which ionizes and contributes to the EC of the solution, and different brands of fertilizer can use different chemicals to make up the total formula. With all of that variability, how can a single "constant" conversion factor be valid?

I own two TDS meters - a Hanna TDS1, and a generic TDShm. When placed in the same solution, they give different apparent TDS values.
...
I typically shoot for 100-125 ppm N in my fertilizer solution, I simply use my TDS meters as a check, knowing that the Hanna TDS1 should show between 380 and 475 ppm TDS, while the TDShm should be in the 470 to 590 range.
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berkman858

Well-Known Member
forgetfulpenguin said:
Most meters measure the Electrical Conductivity of the solution (as well as the temperature obviously) and convert to Total Dissolved Salts and/or Parts Per Million. Results will vary between meters. Whether you use a meter or just look at the plant you have to fine tune until you get good results. I'll use a TDS meter until I've got a feel for the plants' needs/growth patterns, then it's easy to spot when the girls aren't as perky as they should be and do a reservoir change. I do try very hard to make sure I mix my nutrients in the same ratio and concentration after I find a mix that works. My graduated cylinders and pipettes are the cleanest things I own (I even rinse with the solution before use.)

http://www.firstrays.com/tds_and_ec.htm
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The differences between pens could also be due to using different scales to measure PPM. I still think most people posting on this site that list PPM are using a 700 scale or similar.
 
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