No more PPMs for me

[GreatLife4All]

Ok...

I have been doing a lot of research recently into PPM, meters, and etc.

I come from an agricultural background here in the US (midwest). Everything we do with fertilizer is PPM. Parts per million just makes sense to me... I understand it untuitively...

But things change when you start hydro. First, there is the confusion over which meters to use: TDS, PPM or EC. Despite the fact that these all measure the same thing and then use a different scale to represent the result. And then there are the conversion factors... .65 vs .5. All the ag guides that I have ever seen use .5 and all the hydroponics companies use .7 (not even the real factor of .65). I know how to round, but this conversion introduces about 8% error in the PPM numbers.

So I am here to announce that I will never again use PPM on this, or any other, online site. It is simply too confusing. A newbie with a truncheon and no knowledge could read my posts and end up with a deficiency... despite the fact that they will swear they have done everything correctly. Or how about a guy who doesn't know shit about meters... most meters are delivered with a .5 conversion factor. So if you only know about PPMs and I use the ag standard - you are OK. If I quote using he hydro standard, you will get nute burn.

What an UNACCEPTABLE state for any industry to be in. Disagree with the standards established by others. Use incorrect conversion factors... using meters not even designed for hydro... but well water testing instead. There is little wonder that killing plants and deficiencies are a part of our culture with this type of equipment in use.

So I will, from now on, refuse to give any advice in PPMs. Everything I quote will be EC.

Trichomes may get pissed off at me... but quoting anything using PPMs is simply leading to trouble. And it means nothing unless you ask me a couple of questions. Since I never get asked those questions, my assumption is that people don't really understand this.

If you prefer to think in PPM - then it is simple enough to convert. But my guess is that most people don't even really understand what I have typed here. They are probably just like me... they thought that PPM actually meant something... but in the hydro nutrient market - it implies only confusion.

GL4A

 

[Spimp]

Re: No more PPMs for me...

I have a issue regarding your therom. Im not a Hydro grower and im by no means an expert, but I have a little background(not nearly as much as you) in PPm vs EC

If you are mixing a nutrient mixture, PPM is the measure of the additives. Or at least thats what its intent is. If the label says give 500ppm, thats the amount of nutrients to give.
EC is the measure of everything in the mix AFTER the nutrients are in the water. EC measures the already exsisting stuff in your water be it tap, RO or whatever. If the EC after mixed with tap water reads 500, you have no idea how much of what is in there. it could be 1ppm nutrient, 499 ppm city sludge salt.

So Im not sure the way you suggest is good for noob's. For example if the ideal 'feed' is 500ppm, and thier tapwater shows 500ppm, they dont add anything?

You obviously know alot more about this than me, but I just wanted to play devils advocate and educate myself and others with a view from the other side.

Good thread sir.

 

[GreatLife4All]

Re: No more PPMs for me...

Actually, I prefer that people challenge me. We can all learn.

I have a issue regarding your therom. Im not a Hydro grower and im by no means an expert, but I have a little background(not nearly as much as you) in PPm vs EC

Everyone should know this stuff. It is not just for hydro. Anyone who mixes chemical nutrients needs to understand what they are doing. And I am trying to explain this in a way that even a moron (apologies to any self-identified morons reading this) can understand - so if you didn't get it and you are obviously not a moron... I failed at my task.

If you are mixing a nutrient mixture, PPM is the measure of the additives. Or at least thats what its intent is.

Let me start over on this point. You can calculate PPMs exactly (or as close as labeling laws will allow). I have spreadsheets which do it. Most all of the agricultural recommendations (and we are headed there as an industry - don't kid yourself) are based off of ratios developed after extensive testing on crops. We don't have this level of university testing in MJ unfortunately.

All of these recommendations are based off of language like this: 100N 50P 100K. This basically means the plant will grow best if you provide 100 ppm of N, 50PPM of P, and 100PPM of K. These are the target fertilizer levels. But it tells you more than that... it gives you a ratio that you can use to balance the nutrients as well. In practice this means that you can cut the level of nutrients while maintaining the 2 : 1 : 2 ratio between N, P, and K.

When a fertilizer company builds a nutrient recipe - they try to get close to these ideal ratios and levels as possible using common ingredients. But these common ingredients can be very different. You can get calcium from calcium nitrate or calcium sulfate - just depends on whether you need an additional boost of Nitrogen or Sulfur in the mix. Both of these are used by the nutrient companies to build solutions.

Now here is the key... We agree that the plant needs 100 : 50 : 100 - but we didn't specify the level of calcium or sulfur. In actuality -these both have huge ranges of acceptable levels in the plant. So I can build this formula in one of two (actually hundreds) of different ways. If I use Calcium Nitrate - I end up with Ca++ and NO3- in the water. Both of these are charged particles. The charge on the calcium is 2 - the charge on the NO3 is -1 (we can ignore the signs for now). But if I build the same ratio and level using calcium sulphate (because I have another preferred source for Nitrogen, for example), it breaks down into Ca++ and SO2-- (I think - I should look this up, but the charge is -2). But when we look at the charges that each molecule adds to the water - they are very different. We now have added 2 positive charges and 2 negative charges. Without using units - just to simplify things - using calcium nitrate we end up adding 3 charges into the water... and with calcium sulphate we added 4 charges into the water. Please note that in either case, we added 2 PPMs into the water.

If we wanted 200 PPM of calcium - the EC will be 200 charges higher when I use calcium sulphate - but the plant will grow EXACTLY the same under either set of solutions. There is no difference in either the ratios or levels of the nutrients. In one we have some extra sulfur that the plant doesn't mind and a different source of N.

However, there will be a different EC level between the two solutions. And the same PPMs in the areas that matter.

If the label says give 500ppm, thats the amount of nutrients to give.
EC is the measure of everything in the mix AFTER the nutrients are in the water. EC measures the already exsisting stuff in your water be it tap, RO or whatever. If the EC after mixed with tap water reads 500, you have no idea how much of what is in there. it could be 1ppm nutrient, 499 ppm city sludge salt.

You are correct on all points sir. I hope that I didn't lead you to believe I thought otherwise.

So Im not sure the way you suggest is good for noob's. For example if the ideal 'feed' is 500ppm, and thier tapwater shows 500ppm, they dont add anything?

Theoretically, they have no room to add anything. But the numbers you are quoting are bullshit - that was the point of the thread.

You obviously know alot more about this than me, but I just wanted to play devils advocate and educate myself and others with a view from the other side.

Thank you... believe it or not it is appreciated. I have a background in ag and soil science... hydro is weird.

So here is the thing... you are talking about the maximum PPM level - but there is no such thing. There is a maximum level of electrical charge in the water that the plant can take - and this changes daily. I won't explain this, but it has to do with chemistry and osmotic pressure and electrical charge on the particles that are taken in. The higher the EC... the harder it is to get chemicals into the plant. And you can increase the EC to a level where you are stripping nutrients from the roots back into the water. That is why a plant that has too high an EC will turn dry and crispy - the pathways have been reversed and water / nutrients are leaving the plant... rather than entering it through the root system.

Another trick... I can have very low PPM water and get this reversal by using high EC solutions. I can also have very high PPM and this reversal won't occur... as long as the EC remains below the max. So the two cannot be tied together in the way that you think.

The PPMs in the water simply don't matter for what we call "nutrient burn." For hydro, the high EC is ALWAYS because we have added too many chemical salts... so we call it nutrient burn. BUt what is actually happening is the nutes and water are getting sucked out of the plant due to an electrical imbalance.

What EC is actually good for is to ensure that you have mixed the nutrients supplied by a manufacturer in the correct ratios with water. It doesn't matter if they do a silly conversion to 1400PPM or 1000PPM - you have the correct ratio of nutes, you have the correct level of nutes, and you wlll stay below the maximum EC level (3.0 for MJ, but it is strain dependent) that will damage a plant. There is simply NO guarantee that the water contains either 1400 or 1000 ppm of fertilizer.

So back to your example and I am done. You suggested that 500PPM was the maximum that a plant could handle. But assuming that you have a Hanna Meter - what you really said is they have measured an EC of 1.0 and that was converted to a number - 500 and that is the maximum for the plant... according to the meter that you are holding in your hand. If you grabbed another meter (say, a truncheon)... 640 would be the reading when you tested the same water. The water didn't just magically add 140PPM... it is the conversion.

So you can claim 500PPM as the max with your meter... and I would claim 640 is the max with my meter... and we are both actually measuing an electrical potential of 1.0 in the solution. The only trouble is if you use my recommendation with your meter... See the problem?

And no one should grow if they have source water with PPM of 500 under any system without a water test. You will then need to figure out a recipe that works with what is already present.

Hope that I was a little clearer this time.

 

[mehrific]

Well well well....from my experiences, following nutrient recommended dosages always led me into troubles. Using ec or ppm is really the same thing. Like you said its only an 8% error. All ppm pens actually measure the value based on EC and then convert the EC value to display the ppm value, having different conversion factors between differing manufacturers is why we have this problem communicating nutrient measurments between one another. Knowing what conversion your pen has will solve your ppm dilemma. Hanna, Milwaukee 1 ms/cm (EC 1.0 or CF 10) = 500 ppm (.5)......... Eutech 1 ms/cm (EC 1.0 or CF 10) = 640 ppm (.64)...... Truncheon 1 ms/cm (EC 1.0 or CF 10) = 700 ppm (.7)

Always measure your tap water before adding nutes. Its a known fact, high ppm tap water(hard water) causes nothing but problems in a mj grow. IMO, if its over 225ppm, i would buy an RO filter. You shouldnt have your theoretical high ppm tap water problem in the first place.

My point is, I always start off low with my nutrient regimen. If the measured ppm's drop from one day to another, i raise the nutrient dosage by a 100ppms or so. This method gives my plants exactly what they want. I never follow what the nutrient company is telling me to give.

So......i welcome using ec, but much prefer ppm because of its extra detailed values. example....ec = x.x, while ppm = x-xxxx. to each his own.

 

[GreatLife4All]

Yes. These are great tools for doing comparative analysis of your own grow.

Terrible for communicating information to newbies.

I appreciate your input on this thread.

 

[wannabehorti]

Hmmmm

Maybe I completely understand where your coming from

I need a tool to measure yep I don't even copy myself every grow so no one can really copy or feed like I do. And I diffidently comes down to genetics as to what feed they need when. So I by a meter by the solution and try to never change that so I have an idea. But I also only read base nutes not additives

 

[RandyL]

A grower who used to post youtube videos (and who had some very good indoor soil yields) told me that anything with an NPK ratio is considered plant food, and that gets measured to determine the PPM of the mix, things like Humboldt Honey or Molasses will jack the PPM up but it isn't "plant food" as such, and wouldn't be in the water when getting the PPM number. Sound right to you?

I read the above posts with great interest, but I have to wonder if the most correct answer would be to not rely entirely on ppm OR ec.

Maybe the right answer is a combination, like if the PPM is "X", then the EC should be above / below "X".

And what was that about the EC needing to be below 3.0 for MJ plants? Is there a specific range of EC numbers that would be best, and how could you adjust EC after getting the PPM where you want it? I plan to grow indica strains in soil, does that EC <3.0 apply, or would the right answer be another number?

And does PH factor into this in any way?

I plan to buy Hanna meters for all my measuring, to keep a constant standard with all the meters from the same manufacturer.

 

[wannabehorti]

I honestly don't know anything about EC. Randy that exactly why I only read my three part, because once I start adding all the crap the ppms go a little crazy, but I only use it as a check, I usually start low feed up to 1k in veg depending on plant size and where she's burning, I like to stay about 100-150 ppm from burn...... The trickiest thing I like to use is the open sesame(last week in veg -wk3) and cha Ching(wks7+ - flush) by FF and I feel those out and will use the to kinda adjust my ppm with but it sucks. I also like advanced big bud for weeks 3-7


Try reading ppms of a true brew tea....... Off charts to many chunks of shit