nutrient strength/dilution discussion

[Albireo]

I would like to have a discussion on nutrient strength, mostly in regards to dilution. My numbers below are just thrown out there for ease of discussion.

Lets say I have 1 plant under a 2' x 2' screen in a tub (dwc) holding 10 gallons of nute solution. This plant enjoys 100 mL total of my liquid nutrient in my 10 gallons of fresh water and grows at x rate.

Would this same plant under a 2' x 2' screen in a tub holding 20 gallons of nute solution require 200 mL of liquid nutrient to grow at the same x rate?

Since the whole 20 gallons and 100 mL of nutrient are available to the plant, would it not be the same as 100 mL in 10 gallons of solution?

 

[humble1]

nope.
osmosis.
nutrient gradients.
higher level will seek out lower level to equalize.
try it, though, and find out.

 

[Albireo]

So are you saying in the 20 gallon example, I would need 200 mL of nutrient. The plant would use 100 mL and 100 mL would be left in the solution. I understand osmosis, but is this what is actively happening during plant growth (photosynthesis and respiration).

I think an easier way to think of it (at least for me) would be to think in total mass. Again, just making up numbers. To grow a seed to a mature plant, lets just say 1 kilo in total mass, it would take 100 mL of nutrient. Am I correct in assuming there is a direct correlation between total plant mass and total nutrient uptake?

 

[humble1]

So are you saying in the 20 gallon example, I would need 200 mL of nutrient. The plant would use 100 mL and 100 mL would be left in the solution.
Am I correct in assuming there is a direct correlation between total plant mass and total nutrient uptake?

The plant will use what it wants, and what is available to it (pH range). If your mix for 10gal requires 100ml, then you can be sure that 20gal needs 200ml and 30gal needs 300ml etc....
Otherwise your food the plant wants will runout and you'll be left with the leftover food and too much water.
I am not saying that more food is always better, but there is a correlation between available food and potential plant growth (up to a point at which growth flatlines and afterward more becomes detrimental).
good luck!

 

[superusa]

So are you saying in the 20 gallon example, I would need 200 mL of nutrient. The plant would use 100 mL and 100 mL would be left in the solution. I understand osmosis, but is this what is actively happening during plant growth (photosynthesis and respiration).

I think an easier way to think of it (at least for me) would be to think in total mass. Again, just making up numbers. To grow a seed to a mature plant, lets just say 1 kilo in total mass, it would take 100 mL of nutrient. Am I correct in assuming there is a direct correlation between total plant mass and total nutrient uptake?

Plants grow based on the concentration of the nutrients in the solution. This is why people use EC/TDS meters. They don't give you a count of all the nutrients in the buckets, the give you the concentration of the nutrients in the water. 100ml in 10 gallons is 10ml/gal. that same 100ml in 20 gal is only 5ml/gal, half the concentration. Osmosis is not what is happening for the uptake of nutrients by the plant. osmosis is the diffusion of water, not nutrients. In order for osmosis to occur, the nutrient concentration would have to be greater INSIDE the roots for the water to follow it in to even out the concentration gradient.

Regardless, nutrient strength is based on the concentration, not on the total volume of nutrients.

 

[humble1]

In order for osmosis to occur, the nutrient concentration would have to be greater INSIDE the roots for the water to follow it in to even out the concentration gradient.

if he switched tubs from 100ml/10gal to 100ml/20gal the concentration in the roots would be higher than the new solution.
that's all i was saying.
thanks for clarifying, though.

 

[*mistress*]

total plant mass is based on total root mass...

nutrient uptake is only 1-5% of total solution.
95% ofthe solution is water, which should be transpiring & being dehumidified in 24-48 hrs, preferably 24hrs... moves out of veins on leaves into leaf, then into atmosphere.

nutrient uptake is based on maturity of plant, size of plant, light levels & container size, etc, etc....
a plant under 1k+ require more water than plant under 4oowt...
but they may both need same nute levels... water & oxygen important as nutes... maybe more. dry plant matter on 1-5% 'nutrients'... most, by far, carbon, hydrogen & oxygen & water (when wet)...

if measuring a benchmark for nutrient levels, maybe start @ .8 ec/~550 ppm (wand)... & ph 5.0-5.8...

depends on which nute, will get to that 200 mL of nutrient...

5ml= 1 tsp
5*20=100ml, if use only 1 tsp/gal... which, w/ most gh standard nutes, is ~700ppm, or 1.0 ec (nutrwand)...
that is basically bottle instructions for maxibloom & flora nova bloom... or 1-2 tsp/gal...

some prefer to apply more fertilization:
Is any1 else slamming their plants with high ppm?
https://www.icmag.com/ic/showthread.php?t=136683

ran dwc many moon ago, can just add-back @ 33-50% strength solution, to exist mix...
can also just go full strength (maybe 1-3 tsp), then add back water only... until reach volume of initial input... then pour in new solution @ 100%... or, basically, feed-water-feed in dwc set-up... doable. prefer water-feed-water, as long as maintain 1.0+ ec... preferably increase as flower goes on.. to what? only can say for ea strain...

some plant only get .5 meterx.5meter big... & want less than huge grrl that get 2 meter across... both water & nutes, want less...
hard to say what standard... is... unless have cut dialled....
old threads by member Lucas debate 30%-50%-100% add-backs & get to preference of gardener... old Over&row dwc tutorial did 100% add-back, if that correct... miss og... but icmag get there!
also, factor in feeding regime is light levels... low light levels require far less nutes than under multi 1ks' ...
either/or work, especially w/ gh nutes... but, did old dwc w/ supernatural nutes... most work, if keep ph in order... not really over 6.0 or so. 6.2 max...

can either run w/ no res change, or change every 7-14 days... really depend on gardening stlye...

the root ec will steadily increase as the plant creates & stores more food... this food - made during photosynthesis is stored in roots.

1ooog total plant matter does not guarantee 1ooog dry fruit... maybe 25%-40%, if really dial cure.
but this nothoing to do w/ input nutrient solution.

more to do w/ cultivar...
not all fruit same...

maybe this help in calculating strength of nutrien solutions:
calculating npk/nutrient profile
https://www.icmag.com/ic/showthread.php?t=134356

can k.is.s. & just use bottle instructions...
especially if plant in only a 2x2 profile. no need to over feed, if not know nutrient solutions well, or not know cultivar well.

a few dwc threads on icmag... maybe this help:
One for the newbs: cheap and simple hydro, but very effective
https://www.icmag.com/ic/showthread.php?t=13327

Against Bubblers
https://www.icmag.com/ic/showthread.php?t=26021
&
https://www.icmag.com/ic/showthread.php?t=21254

hope this helps. enjoy your garden!

 

[Mr. Greengenes]

More concentrated nutrient solution does not make plants grow faster than a diluted one. Plants take what they want out of the solution and leave the rest. It is possible to convince plants to take more nutrients though. Increasing light intensity and PJJ (plant jiu jitsu) and placement all do this, but it is not possible to force feed them just by using strong nutrient solutions. In other words, plants will grow at the same speed whether just enough nutrients are in solution or almost too much. It's only when the solution is too dilute or too strong that growth slows.

 

[superusa]

if he switched tubs from 100ml/10gal to 100ml/20gal the concentration in the roots would be higher than the new solution.
that's all i was saying.
thanks for clarifying, though.

I wasn't flaming. Just got done getting this pounded into my head for the 40th time in A&P today lol

 

[humble1]

A&P?

 

[og dmc]

anatomy and physiology?

 

[og dmc]

any way I think diffusion is like osmosis for particles. In this case i don't think terminology is the most important part of understanding this concept.

 

[superusa]

anatomy and physiology

Terminology is not important like you said. The real point was that plants in hydro are fed according to the concentration of the nutrients in the solution, not the total volume.

 

[Albireo]

This is the type of discussion I am looking for.

Some back ground on me and what I have going on. I have about 4 years of growing under my belt. I took a 7+ year break. I now have a living and legal situation where I can grow again. Over the past few months I have been building my grow room in a detached garage (along with building my house, rebuilding my trucks diesel, working full time, going to school full time, and raising my 5yo, 2yo, and a third due in may). My grow is prop 215 compliant and I have my recommendation.

I am using PBP and DM for nutes, building my own solution using an excel spreadsheet. I record what I get as far as NPKSCaMg (plus a few more) and TDS. I a 4' x 8' flower area under 2 air cooled 1000Ks. I have a 3.5' x 3' veg/clone area with a 400 watt HPS (soon to be CMH). I will run a 3 cycle perpetual (3 groups of 3 plants; 1 will be 4 weeks 12/12, 1 will be zero weeks 12/12-4weeks of veg, and 1 will be zero weeks veg and then press go and keep it going)

My hydro set-up will be deep large tubs (somewhere in the 20-50 gallon range) under a scrog. The tubs are homemade using 2x material and pond liner. They will be full insulated and will have a lid. All 3 plants per side will be in one tub, with a few airstones and a small powerhead pump. The powerhead will have a sponge filter to promote bio growth. I generally change tub over when I top off with the amount I start with (10-14 days)

if measuring a benchmark for nutrient levels, maybe start @ .8 ec/~550 ppm (wand)... & ph 5.0-5.8...

depends on which nute, will get to that 200 mL of nutrient...

5ml= 1 tsp
5*20=100ml, if use only 1 tsp/gal... which, w/ most gh standard nutes, is ~700ppm, or 1.0 ec (nutrwand)...
that is basically bottle instructions for maxibloom & flora nova bloom... or 1-2 tsp/gal...

see above, the numbers i throughout there were just made up. My nute starting point generally follows the lucas formula NPK and TDS.


some plant only get .5 meterx.5meter big... & want less than huge grrl that get 2 meter across... both water & nutes, want less...
hard to say what standard... is... unless have cut dialled....
old threads by member Lucas debate 30%-50%-100% add-backs & get to preference of gardener... old Over&row dwc tutorial did 100% add-back, if that correct... miss og... but icmag get there!

I miss overgrow as well. I learned a lot there and enjoyed how folks would push boundaries. There were folks who knew there shit from their own experience and they shared much knowledge. I guess they do here to.


1ooog total plant matter does not guarantee 1ooog dry fruit... maybe 25%-40%, if really dial cure.
but this nothoing to do w/ input nutrient solution.

I am talking about total plant matter,including roots. Nothing to do with dry fruit. Is there no correlation between the amount of plant matter produced and the amount of nutrients consumed?



maybe this help in calculating strength of nutrien solutions:
calculating npk/nutrient profile
https://www.icmag.com/ic/showthread.php?t=134356

I use the npk excel spreadsheet that used to float around OG.

can k.is.s. & just use bottle instructions...
especially if plant in only a 2x2 profile. no need to over feed, if not know nutrient solutions well, or not know cultivar well.


hope this helps. enjoy your garden!

Thanks!

More concentrated nutrient solution does not make plants grow faster than a diluted one. Plants take what they want out of the solution and leave the rest. It is possible to convince plants to take more nutrients though. Increasing light intensity and PJJ (plant jiu jitsu) and placement all do this, but it is not possible to force feed them just by using strong nutrient solutions. In other words, plants will grow at the same speed whether just enough nutrients are in solution or almost too much. It's only when the solution is too dilute or too strong that growth slows.

I agree with you (or I think I do). This is exactly what I am trying to say or think about. I love these nights when I just get to get stoned and let my mind go.


I am trying to figure out the size of reservoirs I want to run and it got me thinking about. It is not a $$$ as at my scale the difference in nutes is small.

anatomy and physiology

Terminology is not important like you said. The real point was that plants in hydro are fed according to the concentration of the nutrients in the solution, not the total volume.

This is where I get hung up. It is not that I do not believe you, I just do not understand. This is what I have always thought, until i got stoned and started thinking about it. Care to expand on what you are thinking?

 

[superusa]

This is where I get hung up. It is not that I do not believe you, I just do not understand. This is what I have always thought, until i got stoned and started thinking about it. Care to expand on what you are thinking?

Nutrient and water uptake is done through a couple methods by plants. Water is taken in via osmosis, essentially the water diffuses through the membrane into the roots.

some nutrients are taken up via diffusion, where they diffuse from the stonger (hypertonic) solution in the res to the lower (hypotonic) solution in the root. If the solution outside the roots is too weak, nutirents can't diffuse across the membrane because the solution inside the plant is just as stong or stronger. At minimum you end up with a slower than usual uptake of nutrients, at worst, you end up with a deficiency since the plant is unable to have those nutrients diffuse across the membrane and into the roots, thereby making the nutrients less available.

I believe K is taken up by active transport, essentially a carrier protein brings it through a channel in the cell membrane. Carrier transport happens in cells because they are bringing in K against the concentration gradient (bringing the potassium in when the solution of K is actually weaker in the res than the gradient immediately inside the roots).

Once the nutrients/water have been brought into the roots, the suction/vacuum/pumping action is mostly responsible for the movement of fluid in the plant. Asd the plant respirates and loses water through the leaves, a mild vacuum is created in that area inside the stem. This sucking action brings the water/nutrients up and into the plant.

Hope that helps...

 

[*mistress*]

 

[og dmc]

anatomy and physiology

Terminology is not important like you said. The real point was that plants in hydro are fed according to the concentration of the nutrients in the solution, not the total volume.

this is a good point, essentially this is correct.

 

[superultramega]

It's nice to have some people that understand this on a technical level around here. I love to see the broad assumptions new or less technical background growers make explained by you hort guys.
The more everyone knows about how their plant works, the better off we all are.

 

[highcountrygrow]

biggest growth limiting factor is CO2 conc. at ambient levels (350-450ppm) but plants had evolved in higher ambient CO2 levels (around 1200ppm) so that is what really limits the plant growth nutrient uptake in most gardens. Once everything else is set as far as soil mix and nutrient remind, environment, then the only factor that will limit the amount of water/nutrients that the plant can uptake will be the co2 availability. Look at plant photosynthetic rates vs co2 concentration and you will see that you get a drastic increase in rates between 400ppm->1000ppm then it levels out to a threshold around 1200ppm where increasing past that point does not increase the growth rate/photosynthetic rate.
Again if everything else is set (environmental conditions and nutrient availability) then your most limiting factor to nutrient utilization is via environmental co2 induction (increase to 1000ppm-1200ppm)