Considering switching from PPM to EC, need advice.

Eric Farley

Active Member
I have been growing for a little over a year now and thus far I've always used PPM meters to measure my nutrient concentrations, however I've recently been designing and building an Arduino automated nutrient monitor and the only probe I could find was an EC probe. I was thinking about just converting EC to PPM using a standard conversion formula, but the more I read the more I hear about how inaccurate that conversion is. The only hesitation I have is I don't have any experience or knowledge of it.

My question for you guys is has anyone else made a switch from PPM to EC, if so did you notice a difference in the health of the plants or quality of the final product?

Also was it difficult to find the appropriate EC for the plants? I imagine all I need to do is increase the EC around .2 EC per week instead of 100 PPM and watch for signs of nute burn, but that's just me using the conversion from EC to PPM to figure out what the equivalent value in EC would be to 100 PPM.
 

firsttimeARE

Well-Known Member
Bruh youve been,growing for a year and smart enough to do shit with an arduino but you are asking this?

All it is is a different form of measurement.

Meters use EC already but convert it to PPM and the way they do that is by a conversion factor. To further complicate matters some manufacturers use .5 .7 and 1.0 conversion rates.

For instance Bluelab uses .5 so 600PPM is 1.2EC. It takes EC multiplies it by the conversion factor and,multiples that by 1000.

Or an easier way multiply EC by 500 700 or 1000. So if you wanted to,convert your old ppms find out the scale, say its a bluelab and its 500 scale. Take the 1000ppms you were feeding and divide by 500 to get 2.0EC.
 

whitey78

Well-Known Member
Couldn't have said it any better... you know what your measuring out and feeding your plants already, the ppm/ec meter is just a reference/fuck up preventer... if you doubt yourself the first few times use your ppm meter in conjunction with your other system and note the difference in readings... once your comfortable with using just the ec monitor put your ppm pen in the "in case of emergency/backup" pile...

I keep daily logs of my various res's dwc buckets temps, ppm/ec and water levels... and for awhile I was keeping track of ppm and ec but it became redundant and of no real use so I just stuck with 500scale ppm and the #'s are consistently the same so as long as you know your meter/monitor is calibrated and working properly you really just need to get used to the way the different measuring system works...
 

firsttimeARE

Well-Known Member
I have been growing for a little over a year now and thus far I've always used PPM meters to measure my nutrient concentrations, however I've recently been designing and building an Arduino automated nutrient monitor and the only probe I could find was an EC probe. I was thinking about just converting EC to PPM using a standard conversion formula, but the more I read the more I hear about how inaccurate that conversion is. The only hesitation I have is I don't have any experience or knowledge of it.

My question for you guys is has anyone else made a switch from PPM to EC, if so did you notice a difference in the health of the plants or quality of the final product?

Also was it difficult to find the appropriate EC for the plants? I imagine all I need to do is increase the EC around .2 EC per week instead of 100 PPM and watch for signs of nute burn, but that's just me using the conversion from EC to PPM to figure out what the equivalent value in EC would be to 100 PPM.
How is the arduino coming along? I saw your post on some arduino forum as im trying to build a pH doser as well.

Saw the nMe e farley and thought it sounded familiar.
 

Eric Farley

Active Member
I figured using EC was that simple, I was just concerned I was missing something since people rag on PPM for being so inaccurate, but I suppose it's really just that unless you provide both the ppm and the conversion factor the ppm value could be a number of EC values.

How is the arduino coming along? I saw your post on some arduino forum as im trying to build a pH doser as well.

Saw the nMe e farley and thought it sounded familiar.
It's going well, I've gotten the wiring and parts list all sorted, I'm about 75% done with the code and I should be doing my first tests of the EC side of things tonight. I'm waiting for a bunch of things to arrive in the mail to move on to the next steps. I have a pH meter that seems good, but I can't test it as I didn't have a 10.01 pH reference solution which is required for calibration. Turns out the local shops only sell 4.01 and 7, so 10.01 is in the mail.
 
Last edited:

firsttimeARE

Well-Known Member
I figured using EC was that simple, I was just concerned I was missing something since people rag on PPM for being so inaccurate, but I suppose it's really just that unless you provide both the ppm and the conversion factor the ppm value could be a number of EC values.



It's going well, I've gotten the wiring and parts list all sorted, I'm about 75% done with the code and I should be doing my first tests of the EC side of things tonight. I'm waiting for a bunch of things to arrive in the mail to move on to the next steps. I have a pH meter that seems good, but I can't test it as I didn't have a 10.01 pH reference solution which is required for calibration. Turns out the local shops only sell 4.01 and 7, so 10.01 is in the mail.
I followed rezas build and all he used was 7.0 and 4.0 and recorded the temp at 4.0 cause i guess that matters
 

Eric Farley

Active Member
I followed rezas build and all he used was 7.0 and 4.0 and recorded the temp at 4.0 cause i guess that matters
It seems that different probes have different calibration requirements. The hand held pH meter I have from blueLabs that I've used the last year uses 4 and 7 for calibration. The probe I selected that works with Arduino uses 4 and 10.

Also one thing that seems important is you can't use just any pH meter, most of the ones you find are laboratory probes which are designed to take a reading and be removed from the solution. Extended submersion will destroy the probe. To leave the probe in 24/7 you need to purchase an industrial probe which are more expensive. Although regular cleaning may make a lab device okay, but the whole point of automating this to get get rid of the daily work.
 
Last edited:

The_Enthusiast

Active Member
I used ebay like PH and EC meters, i thought they were ok, but after I switched to HANNA instruments a all-in-one:

And used their calibration, cleaning and storage solutions - i can say my results got better. It has a changeable EC/PH/TEMP "stick"
I was notified that I'll have to change it every 6 months but I used it for 3 years before change. One of better 300€ spent (device + storage/calibration/cleaning solutions for 3+years)
 

firsttimeARE

Well-Known Member
It seems that different probes have different calibration requirements. The hand held pH meter I have from blueLabs that I've used the last year uses 4 and 7 for calibration. The probe I selected that works with Arduino uses 4 and 10.

Also one thing that seems important is you can't use just any pH meter, most of the ones you find are laboratory probes which are designed to take a reading and be removed from the solution. Extended submersion will destroy the probe. To leave the probe in 24/7 you need to purchase an industrial probe which are more expensive. Although regular cleaning may make a lab device okay, but the whole point of automating this to get get rid of the daily work.
Which Arduino tutorials were you using?

Im,currently going thru one.

Trying to figure out a starter kit to buy so I can do the exercises hands on rather than just reading them. There are so many types of boards its dizzying.

So far ive seen dosers made,from,the uno,and the mega2560.

What board are you using?
 

ttystikk

Well-Known Member
It seems that different probes have different calibration requirements. The hand held pH meter I have from blueLabs that I've used the last year uses 4 and 7 for calibration. The probe I selected that works with Arduino uses 4 and 10.

Also one thing that seems important is you can't use just any pH meter, most of the ones you find are laboratory probes which are designed to take a reading and be removed from the solution. Extended submersion will destroy the probe. To leave the probe in 24/7 you need to purchase an industrial probe which are more expensive. Although regular cleaning may make a lab device okay, but the whole point of automating this to get get rid of the daily work.
Whoever told you that leaving either the pH probe or the EC meter in nutrient solution for extended periods will hurt them is an idiot and you should stop taking their advice.

Just don't leave your pH meter in plain or RO or distilled water, it needs some dissolved salts to work properly.

Moving on to the EC question; I use EC exclusively, precisely to BE more accurate. The problem with ppm scales is that there are several of them and often you aren't told which one to use, let alone why. Since they all convert to EC anyway, just use that instead and save yourself the hassle. This is why pros use EC and avoid ppm; to avoid confusion.

If a nutrient manufacturer can't/won't give you numbers in EC, don't use their shit!
 

The_Enthusiast

Active Member
One good trick I picked up from swimming pool construction. If you have a automated system PH probe, EC probe etc its best to put them a bit after PH- injector (with delay of course) so they get cleaned from salt deposits on them.
 

Eric Farley

Active Member
I used ebay like PH and EC meters, i thought they were ok, but after I switched to HANNA instruments a all-in-one:

And used their calibration, cleaning and storage solutions - i can say my results got better. It has a changeable EC/PH/TEMP "stick"
I was notified that I'll have to change it every 6 months but I used it for 3 years before change. One of better 300€ spent (device + storage/calibration/cleaning solutions for 3+years)
Do you leave your probes in the solution 24/7 or do your remove them between checks? I'm guessing this uses industrial grade probes considering it cost so much.

Which Arduino tutorials were you using?

Im,currently going thru one.

Trying to figure out a starter kit to buy so I can do the exercises hands on rather than just reading them. There are so many types of boards its dizzying.

So far ive seen dosers made,from,the uno,and the mega2560.

What board are you using?
I'm not really using any tutorials. I purchased the $100 starter kit directly from the Arduino website to get started learning the basics, that was moderately helpful in that it taught me some basics, gave me a stock of parts that I mostly don't have a use for and helped me learn what to do to ruin an Arduino (or what not to do :p). I was later told by members of the Arduino forum that seemed very experience that whoever wrote the book it comes with lacked any solid electrical engineering background. I've mostly been learning by asking questions on forums, and reading the wiring diagrams and code examples provided from the probe manufactures.

I am using the Uno, I'm hoping I don't run out of memory on the board which would make me switch to a mega. The Uno has just enough pins for the project so it's okay there.

Whoever told you that leaving either the pH probe or the EC meter in nutrient solution for extended periods will hurt them is an idiot and you should stop taking their advice.
I've read this from multiple sources, the laboratory grade probes shouldn't be left in the solution 24/7. I'd be interested to talk with someone else who has tried to use laboratory probes for 24/7 monitoring about how long their probes lasted and how accurate they remained over prolonged submersion, but until then I wanted to make sure I had a probe designed for prolonged submersion.
 

firsttimeARE

Well-Known Member
Do you leave your probes in the solution 24/7 or do your remove them between checks? I'm guessing this uses industrial grade probes considering it cost so much.



I'm not really using any tutorials. I purchased the $100 starter kit directly from the Arduino website to get started learning the basics, that was moderately helpful in that it taught me some basics, gave me a stock of parts that I mostly don't have a use for and helped me learn what to do to ruin an Arduino (or what not to do :p). I was later told by members of the Arduino forum that seemed very experience that whoever wrote the book it comes with lacked any solid electrical engineering background. I've mostly been learning by asking questions on forums, and reading the wiring diagrams and code examples provided from the probe manufactures.

I am using the Uno, I'm hoping I don't run out of memory on the board which would make me switch to a mega. The Uno has just enough pins for the project so it's okay there.



I've read this from multiple sources, the laboratory grade probes shouldn't be left in the solution 24/7. I'd be interested to talk with someone else who has tried to use laboratory probes for 24/7 monitoring about how long their probes lasted and how accurate they remained over prolonged submersion, but until then I wanted to make sure I had a probe designed for prolonged submersion.
Im following a tutorial and struggling with some of the programming parts of it. Im sure by doing the exercises with an actual,arduino would help. Also going to look into another tutorial. Ive seen a couple errors in what im reading,and beginning to question the authors experience.

Im thinking of just getting the BRS 2 part doser that does a slow drip of 1.1ml/min which is really 1.8ml/min according to user review and a milwaukee mc122.

Costs $170 and doing some parts research a doser would cost about $150.

Im,going to still read up on it as its possible to control,lights, co2, pumps, pH, EC, water level all with an arduino,but rather than wait until I learn this is cheap enough. Ill just dilute my pH down on my smaller systems since theres no PLC with this system and might overshoot my setpoint.
 

ttystikk

Well-Known Member
Do you leave your probes in the solution 24/7 or do your remove them between checks? I'm guessing this uses industrial grade probes considering it cost so much.



I'm not really using any tutorials. I purchased the $100 starter kit directly from the Arduino website to get started learning the basics, that was moderately helpful in that it taught me some basics, gave me a stock of parts that I mostly don't have a use for and helped me learn what to do to ruin an Arduino (or what not to do :p). I was later told by members of the Arduino forum that seemed very experience that whoever wrote the book it comes with lacked any solid electrical engineering background. I've mostly been learning by asking questions on forums, and reading the wiring diagrams and code examples provided from the probe manufactures.

I am using the Uno, I'm hoping I don't run out of memory on the board which would make me switch to a mega. The Uno has just enough pins for the project so it's okay there.



I've read this from multiple sources, the laboratory grade probes shouldn't be left in the solution 24/7. I'd be interested to talk with someone else who has tried to use laboratory probes for 24/7 monitoring about how long their probes lasted and how accurate they remained over prolonged submersion, but until then I wanted to make sure I had a probe designed for prolonged submersion.
My probes last for years when left in solution.
 

Eric Farley

Active Member
Im following a tutorial and struggling with some of the programming parts of it. Im sure by doing the exercises with an actual,arduino would help. Also going to look into another tutorial. Ive seen a couple errors in what im reading,and beginning to question the authors experience.

Im thinking of just getting the BRS 2 part doser that does a slow drip of 1.1ml/min which is really 1.8ml/min according to user review and a milwaukee mc122.

Costs $170 and doing some parts research a doser would cost about $150.

Im,going to still read up on it as its possible to control,lights, co2, pumps, pH, EC, water level all with an arduino,but rather than wait until I learn this is cheap enough. Ill just dilute my pH down on my smaller systems since theres no PLC with this system and might overshoot my setpoint.
If you're looking for a way to add controlled amounts of liquids look into a peristaltic pump. The one I've tested supplies 1ml/sec with a simple HIGH/LOW signal to a pin on the arduino. (you need some transistors and resistors to protect the board from being destroyed as I learned the hard way). It costs less than $10.

The one I have and tested against was $25 and I needed 6 total so I ordered some from China for $6 each. I found this link with a quick search through my history, I haven't tried this one but I think it's the one I have in the mail. http://www.ebay.com/itm/like/121372297090?lpid=82&chn=ps&ul_noapp=true
 

firsttimeARE

Well-Known Member
If you're looking for a way to add controlled amounts of liquids look into a peristaltic pump. The one I've tested supplies 1ml/sec with a simple HIGH/LOW signal to a pin on the arduino. (you need some transistors and resistors to protect the board from being destroyed as I learned the hard way). It costs less than $10.

The one I have and tested against was $25 and I needed 6 total so I ordered some from China for $6 each. I found this link with a quick search through my history, I haven't tried this one but I think it's the one I have in the mail. http://www.ebay.com/itm/like/121372297090?lpid=82&chn=ps&ul_noapp=true
http://www.bulkreefsupply.com/brs-2-part-doser-1-1-ml-per-minute.html

This was the one I was looking at. It plugs into the wall and can be operated by a simple relay.

Do you have a good sketch to use?

You said you were a programmer right?
 

Eric Farley

Active Member
http://www.bulkreefsupply.com/brs-2-part-doser-1-1-ml-per-minute.html

This was the one I was looking at. It plugs into the wall and can be operated by a simple relay.

Do you have a good sketch to use?

You said you were a programmer right?
Yes I am a programmer, although this is my first time writing this language, but they're all more or less the same.

I don't have a complete sketch for anything yet, but the sketch to run the pump I bought would just be something like.
Code:
const motorPin = 3 // this could be any available pin.

init () {
  pinMode(motorPin, OUTPUT);
}

loop() {
  if (runPump) { // this would be some indication that you want to turn the pump on, for me it's if the PH or EC is outside the acceptable tolerance I'm giving it. This could be simple or complicated depending on how you want to determine if the pump needs to run.
    digitalWrite(motorPin, HIGH);
    delay(1000); // this can be anything, in this case I'm choosing to run the pump for 1000 milliseconds [1 second] which equals 1ml
    digitalWrite(motorPin, LOW);
  }
}
That's very simplified as I'm not sure what exactly you're looking for when asking if I have a sketch. There are other concerns to consider also such as how do you determine if you should run the pump, how often should you run the pump and when was the last time the pump ran. For example my PH I want to check every hour, and the EC I want to check only once per day.

I'll be sharing my code, part list and build once it's complete but that could be a month or more. I think I'm going further than you're looking for though as I'm doing a touchscreen that allows me to monitor the PH and EC of the DWC system, set the EC levels, set the acceptable tolerance for the EC, purge the pumps to get air out of the lines, turn some motors on/off depending on if I'm using those nutes at that phase of growth, a flush mode that runs both EC and PH adjustments on a more aggressive schedule to get the soup back up to the correct EC/PH rapidly after a flush. Maybe a couple other features that I'm forgetting atm.

Aigh so much work to do! This EC meters code is causing issues atm so time to get back to that :/
 
Last edited:

im4satori

Well-Known Member
a nice pen is made by Myron

they last about 2 or 3 times longer and theyre good at warranty

the pens are a bit expensive at $140 but there good pens

they have the option to set the ppm at either convertion or use EC

but I also agree the EC is better
 
Top