Why PPM?

[jadins_journey]

I never meant to say they're not important, more just trying to point out that neither EC, CF or ppm is perfect or in any way better than the other. To be truly honest they all are false numbers in one way or another. I use my meter and the numbers it shows me as a baseline, something to compare to i guess. If my meter says 1000ppm at one point and then 1200ppm at another point, then that tells me there's been a change. Doesn't tell me anything more than that. Unless for some reason you use several different meters from different manufacturers randomly for the same grow, it's all relative.

:yes:yes Exactly! Could not have said it any better Johnny

jj

 

[The Joker]

For me the bottom line is, it allows me to measure what the plants can take. I use a truncheon meter. I keep notes on how the plants do. If I know the plants burn at week 5 with a ppm of 1000 I back off. I've had other plants burn at 1400 and some show no signs of nute burn.

So different plants have different needs and it's a useful tool to see what the plants like.

If you have nute lock out for whatever reason , you will see the ppm rise as the plants only take H20. That's anecdotal, but poking the meter in has averted disaster for me.


But nothing beats watching the plants, their color, the leaf shape and the rate of growth.

 

[Redux]

I totally agree it almost does not matter what the reading really is if you use it as a baseline for your setup and monitor and adjust accordingly. The bottom line with this whole discussion for me is PPM is arbitrary based on a Conversion Factor/Formula FROM EC and when we talk EC it's the same language otherwise French/Greek/English regarding the PPM thing.

 

[JayBee]

Redux, it seems like you are only one who got point of the thread :)

Point i was trying to make is: If all meters that measure EC (or CF) or PPM are able to read out in EC, and that EC reading is consistent across all manufacturers, then it seems crazy for us to talk about PPM!!

On the other hand, if meters from different manufacturers either do not have option of displaying EC/CF or if meters from diff mantufacturers will have different reading for EC, then obviousy EC would be no more informative than PPM.

For purposes of sharing information, when we post about nute levels, if we talk about EC it is a value that we all read the same no matter which meter we have. On the other hand if we talk about PPM the only way to know what the writer is talking about it to have same meter or find the formula to translate their ppm back to EC/CF. So it just seems that when posting on a forum using EC or CF instead of PPM is a no-brainer.

Final note, I am not meaning to take anything away from the other posts in this thread that I think make very important points.

Best regards,

JB

 

[Rootbound]

My meter does not have a conversion factor. It measures the TDS and tells me how many Parts Per Million of Total Dissolved Solids I have in my mixture. When you talk about EC it gets confusing for me. You need to know what country they are from to figure out what conversion factor they use. PPM makes the most sense to me. ROOT

 

[The Joker]

Jaybee and Rootbound:

That makes sense...

I have a truncheon which shows EC, then a .5 and a .7 conversion. So it's really kind of arbitrary for the one you choose. But if EC is more universal then that makes sense.

 

[Redux]

When you talk about EC it gets confusing for me. You need to know what country they are from to figure out what conversion factor they use. PPM makes the most sense to me.

Well you actually have it backwards regarding this discussion as EC is universal and PPM is not in this case. Yes...technically PPM is parts per million but what meter manufacturers do in this case is the equipment actually reads EC then they use some type of programmed chip or circuity to translate that reading (Conversion Factor) to display a PPM. In some way that really does not make sense and understand the confusion.

I work in an industry where I send samples in on a regular basis to genuine labs for analysis and some of that has been PPM work determining element concentrations. Yes it seems PPM should be parts per million and a part per mil is a part per mil like mg per 100 gm or something but in this case the lab reports tell me what's in there and I don't need any conversion. They use things like Atomic Absorption where they're measuring the amount of atoms of a particular element in a given sample size and not something generic like conductivity.

Siemens are a standard unit of measurement that quantify the amount of electrical conductivity of a solution between a standard distance. It is typically expressed as milli or micro siemens when us growers talk and I usually go with micro...like 2200 or at a .5 conversion ='s 1100 ppm while some might say 2.2...which is milli siemens...same thing.

Someone else in this thread mentioned something like EC/PPM really is only a gauge and does not really measure nutrient strength and from what I understand that's true...it only measures what is measurable with the equipment used and there are nutrients, or things available that a plant can use that don't add to EC. Amino acids don't conduct...do they? What about hormones? EC/PPM readings provide a baseline for the conductive salts mainly.

Pretty sure that's close...lol.

 

[Rootbound]

Great post, You are correct. Sorry for the confusion .. ROOT

 

[brookky]

Sorry to change the subject ,but what brand of meter is a good one to have in the us?

 

[JayBee]

Blue Lab truncheon for EC/PPM is best and easiest.

 

[brookky]

JayBee where can these be found at?

 

[TheNman]

I use ppm as i have a ppm meter.

I'm not going to convert it to ec every time i post.

Plus, what's the variance of the different conversion rates?
A couple %?

Just be glad that everyone doesn't just say what dosage of the nutes they're using! :D

 

[JayBee]

Nman- Does your meter only read out in PPM or can it also read out in EC/CF? FYI the variance is quite large, divide by 500 vs divide by 700 if I am not mistaken. Obvioulsy if your meter only reads out in ppm, and if that is common to most meters in your region, than talking about ppm would make sense. However if your meter DOES read out in EC or CF and if most meters do, then you should reread great explanation made few times by Redux.

Brooky- Everywhere. Start with Google and if you have problems finding them shoot me a pm and I will give you more info ;)

Really funny this is longest running thread i have started...

jb

 

[Jalisco Kid]

Buying meters is like buying a hooker everybody has there preference. I would buy what your local store swears by and will replace it with out asking questions. Blue lab had a lot of problems with their equipment a while back. I use Hanna because when it will not calibrate right I take it back for a new, no questions asked. JK

 

[Redux]

Plus, what's the variance of the different conversion rates? A couple %?

Uhhhh...I saw someone totally destroy a grow. Could get into a bunch of boring details but it's not 'just' a couple of %. It's at least enough to have a major impact possibly to the point of annihilation...no shit.

 

[Jalisco Kid]

.5----------------- .7
1000 ppm-------- 1400 ppm
1500 ppm-------- 2100 ppm

 

[grizz]

JK what do you think of the tri meter? are they worth the money and dependable.

 

[johnnyballbag]

Uhhhh...I saw someone totally destroy a grow. Could get into a bunch of boring details but it's not 'just' a couple of %. It's at least enough to have a major impact possibly to the point of annihilation...no shit.

No offense man, but that dude was obviously playing with fire by pushing it that far. If he had it all dialed in, he'd know how to mix his nutes and therefore wouldn't have added enough to destroy his shit. People seem to forget, it's a plant that's flourished outside for thousands of years, it can take quite a beating. So to destroy his crop, he must've added WAY too much. I know i personally wouldn't start ramdomly adding double the nutes i normally would just 'cuz i bought a new meter. It def IS a big difference, but in the whole point of the thread, ppl are going to use what's most accessible and/or easiest for them. Someone put up a pole and see how many farmers are willing to change something like that for the sake of posting...bet i'm at least close to right. ;) Again, just sayin...

 

[snowkitty]

To the original poster...GREAT QUESTION! and I learned this one the hard way. I had a NutraDip tri meter and didn't know it had a conversion factor of 0.5. In fact...I still don't even know that officially but I read it on an information pamphlet that an online hydro store I trust put out. The store is BGHydro and they've got some good info on EC/TDS meters if you pop over to their site.

Anyway...yeah...I think I overfed and fucked over my plants by using different meters...and I didn't understand the difference between my Hanna hand-held and my Nutradip tri meter. When I learned that Hanna is 0.7 conversion factor and the NutraDip tri meter is 0.5 a big light bulb went off as I smacked myself in the forehead.

So, what you really wanna know is what units your nutrient schedule is in...and then buy a meter to that conversion factor. or else you are converting all the time.

In my case, my feeding schedule is in ppm with a 0.7 factor, so I went with a Hanna meter that I can default to 0.7 (or change to 0.5 if I want...it's the Hanna Gro'Chek). I'm getting rid of the Tri Meter. It's great if you want to use a 0.5 conversion factor.

So yeah, why anyone talks in ppm is CONFUSING AS HELL because it made me overfeed my plants when I was using a meter that didn't match my nutrient schedule.

:animal0048:

 

[blackone]

I'll definitely cast in a vote for EC also, since as said before if someone gives you values in PPM it's almost useless information unless they tell you what meter/conversion factor they're using.