Beener

1st of all...I'm referring to the nute concentrations in my hydro grows. I haven't made soil comparisons yet...but soon.

Does anyone else have to run their nutrients very low for their hydro grown clones? So far, after 4 different cultivar grows through the same system. There's been a rock solid trait regardless of strain....or nute brand. I can't push nutes past 250ppm.

Depending on the NPK, I will either experience Nitrogen toxicity, which appears as a full leaf Eagle Talon effect. Or P&K toxicity, which manifests in the leaves, and slowly burns them unitil they're fully chlorotic and brittle. This will start as a rusty pattern, and continue until the effected leaf has died.

I've toyed around with NPK's and concentrations to confirm cause and effect. I can control the Eagle Talon by adjusting Nitrogen. As well as avoiding the full leaf burn by leaving the ppm at 250 or lower. I can make them appear, and make them go away by adjusting nutes, so I have no doubt what the cause is. The question is why?

I've grown several different strains. Even a pure Indica that I've grown in soil many times...and proved to be a nute slob. I've used 2 different brands of base flowering nutes, and 2 different brands of P&K supplements in several different combo's, and regardless....the nute ceiling is about 250ppm.

My clones flower at approx 24", so I realize they're small by comparison. Though clones that were allowed to reach 36" at peak flower, couldn't handle any more nutes than clones flowered at 20".

The quality of finished buds have been excellent. None of these symptoms visually effect bud sites. But I can' help but think there must be an effect.

Then on the otherhand...I end up coming to the conclusion that if the plants are saying that's enough....then that's the best indication that they're getting what they need.

My other thoughts are in the system design. I built my own set-up, and provided a great deal of air supply. Not only in the rez, but directly in the root zone of each plant. I over sized air pumps for max delivery, and designed some characteristics into the system that further add to dissolved oxygen (D/O) supply level. I also run my solutions at a 69*F avg, which allows the solution to hold even more D/O before saturation.

Can max D/O saturation have a positive effect on plant nutrient uptake efficiency? If so...can it have this much of an effect? I haven't tested my D/O. The point of overkilling the supply, was to not have to monitor it .

It's reeeaaally puzzling to me. For the most part...It appears to be a good problem My last harvest was 4 oz's of fully manicured and dried nugs. Excellent to very good quality on all fronts.

Strange...with all the reading I do everyday, I've never heard anyone else mention a similar situation. I haven't seen a problem that I can attribute to this. It's just a mystery that's starting to bug me.

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Beener

nemesis050

i wouldnt go more than half strength on any hydro nute.....it seems soon as you do...burning starts....

yeh beener i too have found that high strength nuteing is not the way to go.

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panamajuice

Beener,

250 ppms sound very low... I don´t have much experience but I´ve read most people have their ppms around 1000 during flowering.

It must have something to do with your setup, if you have tried diferent nutes and diferent strains with the same results. Maybe something to do with your massive air supply???

I

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penguin

Hi Beener

Interesting situation. I would hazard a guess that it's probably because the meter is telling you the electrical conductivity of the ionic components of the solutions, but because you're using organic nutes, most of the minerals are bound into organic compounds and not conducting.

In priniciple, more oxygen in the root zone allows a higher rate of respiration (faster metabolism), higher rate of uptake, and higher rate of assimilation. So higher DO levels should be reflected in higher EC requirements.


penguin

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adamx

From the sounds of it I'd agree with pengion. The TDS meter is measure'n the electrical conductivity. When was the last time you calibrated the meter, and what kind of meter is it ?

Ive had to throw out a few because the electrode on them gets corroded and whatnot with age, and then it wont give you a reading worth a . Also, I had an issue with my 0-1999 meter giving me readings of 250-500 max, and it turned out the battieries were getting low. Took me 2 days of headaches to figure that out.

As far as dissolved oxygen goes, if you have any concern at all that your plant isnt getting enough oxygen, then give it more. Get another bubbler if you have to, or just get better diffuser's. A pair of bubble wands keeps a solution well oxygenated with a 1500+cc/min air pump. Tho even I get concerned as I usually run a DWC setup and oxygen is crucial to the plants survival. My trick is useing 35% Hydrogen Peroxide (H2O2) at a rate of about 1ml / gallon and I add another 1ml per day if i remember to. H2O2 is just die'n to add oxygen to your water, and after it breaks down release'n the extra oxygen, all thats left is plain ol H20.

Also, what PH is your solution running at. That can cause alot of issues with nutrient uptake and lockups. If you dont have a PH Pen then go down to a petstore and grab a midrange fishtank aquarium ph test kit. There should be a kit with a range of approx 6.0 - 8.0. If you do have a pen, buy calibration solution, calibrate, and toss it if it wont calibrate. Optimally you want to try and get your nutrient solution to shift back and forth from 6.3 to 6.5 optimally.

Hydroponics is a science as much as it is an art.. and without accurate measurements, no science works.

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--adamx

Ask not what your pot can do for you,
But what you can do for your pot.

daltron

Hey Beener, how U B ?
I run a recirculating DWC system with close to max DO with a average res temp of 68*F .......what I have seen:
.......seedlings = a max ppm of 750 to 800 regaurdless of strain
........clones flowered at 18" to 24" = a max ppm of 300 to 400 regaurdless of strain

Currently on my 3rd grow with this system, so I am still learning how to maximize the system for best results......but I think the results are close enough to your results to confirm your results.......

I'm not sure of why, but it does seem that:
.........more oxygen = less nutes
.........less oxygen = more nutes

for me the bottom line has been increased yield with good tasting buds

Not being a chemist I can't help but feel that I am missing something.......so I would guess that having plenty of free oxygen molecues allows the nutes to combine with the oxygen for easy transport into the plants, while without all that O2, one must saturate the nute solution with nutes to force the uptake......looking at NFT and the airo method, both supply a large quanity of oxygen and both methods tend to use less nutes too.....

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adamx

Close.. but as far as I remember from biology, oxygen doesnt combine with the nutes for uptake, it simply provices the roots with the oxygen they need to flourish. To quote penguin above my previous post...

In priniciple, more oxygen in the root zone allows a higher rate of respiration (faster metabolism), higher rate of uptake, and higher rate of assimilation. So higher DO levels should be reflected in higher EC requirements.

In short what that means, is more oxygen means healthier roots, means more nutrient uptake, means more nutrients required in the solution, resulting in bigger fatter better buds.

__________________
--adamx

Ask not what your pot can do for you,
But what you can do for your pot.

penguin

Nutrient uptake is an active transport process, meaning that it requires energy. The energy is supplied by respiration, which occurs in the mitochondria. O2 + C6H12O6 => CO2 + H20 + energy. Lack of oxygen limits the rate of respiration, and therefore the rate of uptake.

Assimilation (the incorporation of nutrient elements into biomolecules) is also an active process requiring energy that's derived from respiration, so the rate of assimilation is also governed by available oxygen.



penguin

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Beener

Thanks for the replies guys. Dalton...knowing that you have basically the same situation, makes it appear more typical. Which was what I was wondering. I didn't know if it was just me...or what .

adamx - The meter is new, and I keep it calibrated weekly. I also chart calibrations (out of habit), and have not noted any drift. Well...the meter's nearly new.

I spent many years in a lab environment, so I tend to take care of my gear more so than most. Because of my background...I can safely grade the quality of my meter, and have the hands on experience to know when somethings wrong.

I keep fresh buffer solutions, and never re-use them etc. Rinse with multiple DI water rinses after each use, and properly store the electrode in a solution.

Penguin - As usual...I think you nailed it. The studying I've done since posting this thread leads me to believe that the "Organics" do play a role in how the meter functions. I wasn't surprised to find you posting this info as a possibility

Well..it's all running great. I have no complaints on yield or quality. It just bugs me when I can't reason my way through a situation with a degree of certainty. With me, It's usually not enough to know something is functioning properly...why or how is just as important. Just a personality quirk I suppose. Thanks again

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Beener

penguin

I dunno, just a guess man.

Daltron's low EC suggests that something else might be involved, as GH Flora Nova are not organic nutrients (but he does innoculate).

You're both running what are essentially DFT systems. My experience with a similar system (recirc DWC) using non-organic nutes and no innoculations was that the plants prefer EC in the "normal" range, i.e., around 2.4 total. This has been true for both plants grown from seed and from cuttings.

As long as the plants are happy it's all good, but I am also curious to understand what's going on.


penguin

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