Discussion of the pragmatic application of LED's

[guest456mpy]

Hi alkalien,

Wow 1st Hydro and 1st LED at once, you are brave indeed!
I did the very same thing when I switched, btw. that's how I know.
Ran into the same Mg def in veg, K in veg and flowering. I now have separate Cal and MG solutions so I can balance the nutrients without adding extra N that's in CalMag. I'm hoping a more detailed discussion of nutrients will follow our treatment of lighting per se. I think we are wrapping up light quantities and strengths and ready to move on to qualities, but who knows what direction this thread may take.

Thanks for your input!
H.G.

 

[alkalien]

Hey Hempyguy,

it's not like I'm a experienced grower at all, just made a few observations running LEDs. I used to grow outdoors and even that has been few years ago but then I decided to have a go again. This time indoors since there is no more outdoors arround here any more. Read all the stuff I could find and then finally decided that to try LEDs. On planning the setup I noticed how much I hate dirt and made it a hydro system. Of course I risked loosing my first harvest but why risking your harvest twice on changing the setup twice?

I guess my lack of experience should warn you not to overestimate my input, although I did quite some research and do have the insight to understand the higher theories you are discussing in here.

Two other thing I encountered were that my plants hardly stretched after switching to 12/12 and that it took quite some time after switching for them to start flowering.

Because of that I started to doubt my panel and am now going for a new one. Mine uses about half and half red and orange bins the red ones beeing 3W and the orange ones beeing 1W bins, at least I assume. There are some blue, green and other ones in there too, but only few compared to the majority of red an orange ones.

I decided to order a custom made pre-build unit from China, 300W but am still researching on the colors. At the moment I'm leaning towards using 80 to 90% reds (50% 630nm and 50% 660nm) and the rest blue and white, perhaps adding some 740nm far red. I'll let you know once I got it built and sent.

Sorry if I went to far into my pragmatic application

cheers

 

[guest456mpy]

alkaien,

All observations based on experience are welcomed here. By experience I mean that you have actually observed what you express, not that which one reads elsewhere. In knna's case he has access to a group of growers that collect data for him, which IMHO resolves to actual observation. I never intended to mean that one needs years of experience to make a comment.

In the same way by "rules" I don't meant a set of statements used to control any persons behavior, but rather a set of instructions which, if followed correctly, will result in a baseline successful grow which can be later dialed in according to actual local circumstances or variables.

English is such a "loose" language and I take things in a quite literal way, which can lead to misunderstandings.

Thanks again for you very valuable input!

H.G.

 

[alkalien]

haha, that's how I did understand you in the first place. It's just whenever I discuss with people it's of interest to me how they made up their minds. So I wanted to give you the information you need to judge on my skills since I'm pretty sure this is something essential to every debate. I can find quite some information about your experience, I read literally every post by knna on LEDs, even followed hin into the spanish forums and I found a lot of interesseting posts from the Weezard on how to DIY LED Panels.

This post can of course be deleted, doesnt really add anything to the discussion. Just to make sure you know I didnt misunderstand you.

cheers

 

[one Q]

thanks to all.

thanks to all.

WEEZ= I didnt mix up the vent needs but just misunderstood the scrub thing, which I feel silly about last night after posting.

TREEFROG= I like the reverse Vent setup idea. thats nice.

 

[joe4444]

In the same way by "rules" I don't meant a set of statements used to control any persons behavior, but rather a set of instructions which, if followed correctly, will result in a baseline successful grow which can be later dialed in according to actual local circumstances or variables.

Instead of rules how about guidelines?

 

[guest456mpy]

Instead of rules how about guidelines?

Sounds fine to me, how about everyone else?

H.G.

 

[knna]

Yep, HG, the mooning person was directed to the rule For me, as far as "rules" are clearly stated to be general guidelines, its good.

But I think that on our starting period of learning how to get the best of LEDs, rules may be detrimental, as it tend to keep people away of trying new things. Open mind usually dont match fine with rules.

The point about the "K defficiency" of treefrog puts on the table an aspect very important that we should dedicate more time, if fertilizing plants growing under LEDs is somewhat different, that I think so.

The pattern of the K deff is common to some other problems, and often its misdiagnostiqued it instead of the actual cause. The browing of edges (advancing to tip) of the leaves, sometimes acompanied with a chance in texture of the leaves (becoming brittle) is caused by bad regulation of leave's stomata. It happen too when there is radicular damage (roots drown, mechanical damage, hard swings of ph, cold), when there is little CO2 (not enough air renovation) or when salt's concentration around roots is high and difficulties the uptake of water. Thus in general it happen when for some reason water uptake is difficult (or CO2 low), and plant reacts closing stomatas to avoid dehydration.

LED growing clearly reduces transpiration and water uptake, due the reduced temperatures and, more important, the lack of InfraRed. Less water uptake obligue to make some adjustements.

First one, as we water less, in order to provide the same amount of fertilizer, its concentration must be higher, in proportion to the reduction in water uptake. Resulting EC may be high enough to make more difficult water uptake due reduced osmotic pressure gap (between roots and surroundings), and cause symthoms as of overfert ones.

On the other hand, while most elements are uptaked actively by roots, there is one mayor nutrient that is not, Calcium. Its absorbed passively together with water. So the reduced water uptake may cause a Ca deff. Although I ve seen some cases, they was little compared to the people that hadnt the problem, so fortunatelly its not critical, but probably using an slightly higher concentracion on Ca would be desiderable when growing with LEDs, or at least, ensure other things that may interfere with Ca uptake by reducing its solubility (as too high or too low ph or cold temps) are not present. Ca deff Ive seen happened mostly when grower was unable to keep rootzone temps high enough.

BTW, I believe with LED growing we should lower a little the yield target from a given space area (compared to HPS growing). One of the reasons is the increased nute concentration required, which may be problematic (think that for a 30% reduction on water uptake, a base EC of 1.5mS needs to raise to 1.95) and makes more difficult to push toward max production of a given space.

The other reason is about light. LED spectums works with much higher efficacy than HPS ones at low irradiances. HPS growing only works fine at high light density levels, due its spectrum so rich on yellow-orange ask for it. With average densities below 500uE/m2, HPS usually are unable to get good buds. While with LED spectrums we are being able to get nice budding at 300uE/m2, and very good at 400uE/m2, with an efficacy of light near double.

But as we increase the light density of typical LED's spectrums, efficacy goes dropping. Its possible to grow with LEDs at high irradiances, but efficacy of light in this case, although still better than that of HPS spectrums at same irradiances, is far from being double. This is an empirical observation.

I believe its due the caracteristic of red photons of saturating photosynthetic systems of leaves, thus past some irradiance of red photons, they add little more. This happen too, at less degree, with blue, that anyway is not useful in large amounts to beat other spectrums as HPSs due its reduced photosynthetic efficacy, while green-yellow photons are way less affected and can continue increasing photosynthetic rate up to very high irradiances.

Practical consecuence is past some critical levels of irradiance, LEDs spectrums dont work much better than others, as HPS ones. While using half light we can get yields over 80%, if we want to yield same than a HPS, we need to use an amount of light near the one used for the HPS (say, 80%), and its expensive, apart of involve other problems, as the cited with elevated EC. And thats is distributing the light very evenly as we did, Im afraid that when using brick style LED panels, acheving same yield per sq meter than with HIDs will require to use near the same amount of light.

While accepting an small reduction (say, 10%, no more than 20%) on target yield makes all way easier and allow to very strongly reduce Watts installed, meaning lower initial cost and lower electric bills, and get very high productivity figures.

I want to mean that although having a yield for space unit same than with HPS is doable, best adaptation to LED growing may involve to lower the yield target (per unit area) a little, so this way is how LED lighting works better.

If for a grower, yield per unit area is priority, in general for a while HID would work better. Although LED growing may overcome the problem by allowing stackered growing, due the more compact plants being grown, the small distances required between lamps and plant, reduced venting need, etc. It may allows in many case to use two bloom chambers over the other, thus getting a huge increase in yield per unit area using a similar amount of watts.

 

[knna]

My past post was large and I was interrupted while writing it, so there was some post inbetween that I didnt see until I finished.

so about fertilization, I would like to add that what treefrog described may be K deff aswell. But probably caused by excess Ca (and probably, Mg) in the media. K is well uptaked when its present, and as formula was the same than worked fine with HPS, the problem must be related to it not being enough in the media.

Can you detail how were temperatures in the LED chamber, treefrog? Did you tracked water consuption? Was it much lower than when growing with HPS? If so, how much? Do you know the nutrient profile you used? Did you used different ECs? I feel tracking these issues is the key to improve our LED grows.

 

[guest456mpy]

Doh!

Doh!

originally posted by knna

Yep, HG, the mooning person was directed to the rule

knna, The very fact that you felt you needed to reply to this makes me sure that I didn't communicate sufficiently to you. But it is not an entire loss.

I have formulated Hempy Guy's first law of engineering humor:

Rule 1: Engineers seldom make successful comedians!

In short I was trying to lighten up the mood in the thread and entirely mucked it up in the process. My apologies if I offended in the very slightest!

The rest of your post is chock full of information as usual.

The Ca locking out K and Mag is very likely the root (ouch) cause in soil and coco, but how about in DWC? I'm not trying to refute your answer, but asking for clarification as this was the medium I was using when I experienced my only exhibition of this on my very first LED grow. I was not using GH 3-part flora for that grow and since using GH @ 6:0:9 ratio ph'd 5.5-5.9 I have not seen it occur again.

Also how might ph affect this "syndrome".

With greatest respect,
H.G.

 

[alkalien]

I was thinking I was dealing with a lockout of Mg by Ca and switched to RO water, the problem remained until I added extra Mg.

I can log pH and EC values over my next grow if this would be of any help.

 

[Weezard]

I have personal experience with DWC under leds.

I have personal experience with DWC under leds.

"The Ca locking out K and Mag is very likely the root (ouch) cause in soil and coco, but how about in DWC? "
<groanly grin>

That would depend on the water you start with, yah?.
CaMg def. is seldom an issue in soil.

With R/O, distilled, and rain water a li'l CaMg is usually necessary to keep what you already have from being sucked out by the too pure water.
It's an osmosis kine sing.

Most mainland tap water has plenty Ca.

Us Volcano dwellers, (yah, I know we're out of our vulcan minds), have surprisingly pure well water.
About 110-120ppm and it's low in Ca.

With Coco, I learned that you only need a bit of CaMg in your first wetting and again when you switch to flower.

With DWC it goes in with every res. change of course.
But, caution is advised.

"More than enough is too muckin' fuch." - W

Overdoing it will turn your stems bright red. (An' my face as well).


I assume it's a phosphorus lockout caused by excess CaMg.
Anyone know for sure?

Aloha,
Weeze

 

[knna]

originally posted by knna
knna, The very fact that you felt you needed to reply to this makes me sure that I didn't communicate sufficiently to you. But it is not an entire loss.

I have formulated Hempy Guy's first law of engineering humor:

Rule 1: Engineers seldom make successful comedians!

In short I was trying to lighten up the mood in the thread and entirely mucked it up in the process. My apologies if I offended in the very slightest!

I was almost sure it was a joke, HG, but I dont know you enough to be sure, so I prefered to clear it up. It Weez posted it instead you, I wouldnt feel the need (BTW, these threads would be different if Weezard not apport his invaluable sense of humor, apart of very precise observations ).

Glad to know that we can talk about serious things while having good laughts.

The rest of your post is chock full of information as usual.

The Ca locking out K and Mag is very likely the root (ouch) cause in soil and coco, but how about in DWC? I'm not trying to refute your answer, but asking for clarification as this was the medium I was using when I experienced my only exhibition of this on my very first LED grow. I was not using GH 3-part flora for that grow and since using GH @ 6:0:9 ratio ph'd 5.5-5.9 I have not seen it occur again.

Also how might ph affect this "syndrome".

With greatest respect,
H.G.

I havent grown in DWC, but I think its going to be way less of an issue there as far as ph is kept in good ranges. At 5.5-5.9 Ca uptake should be very good in a water culture. So I think your problem maybe was caused just for a bad nutrient profile, probably with a too low Ca percentage (do you know it?)

Generalizing, in DWC slow water uptake may lead to Ca accumulating in res, but that is something easy to solve by periodical dumping off.

But still in DWC, the problem with Ca deff due low water uptake may appear. Extreme phs lead to Ca forming insoluble compounds, so they must be avoided, but the valid range is large (a little over 5 up to a little below 8). On the other hand, cold reduces solubility, apart of reduce water uptake. So too cold temp is something to avoid on out LED grows. I always though that in water cultures ensuring water temp dont go over critical temps is good, but its not good either to allow too low temperatures.

 

[guest456mpy]

Originally posted by Weezard...

That would depend on the water you start with, yah?.
CaMg def. is seldom an issue in soil.

Absolutely. Any fool (and that means me btw) should have known that. But I was young in the ways of hydro. Still wet behind my ears. And using some free non major brand nutrients a friend gave me. On my first LED grow. What a recipe for disaster, eh?

For the next grow I stocked up on separate Cal and Mag solutions, just so I didn't have to add extra N, but nary a symptom with the formula mentioned in my previous post.

Probably should be treated as aberrant data for all practical purposes as I kept no records of that grow and and the nutrient formulation is unknown. It was entirely curiosity on my part with no conclusions necessary.

Peace and productivity to one and all,
H.G.

 

[knna]

I was thinking I was dealing with a lockout of Mg by Ca and switched to RO water, the problem remained until I added extra Mg.

I can log pH and EC values over my next grow if this would be of any help.

You can grow with excelent result withough tracking ph and EC. But when you want to extract conclusions about anything, and especialy about fertilizing, tracking them is invaluable. Especially when some problem appear.

Fully agreed Weez answer.

 

[knna]

Overdoing it will turn your stems bright red. (An' my face as well).

View attachment 77950
I assume it's a phosphorus lockout caused by excess CaMg.
Anyone know for sure?

Aloha,
Weeze

I wouldnt jump on the wagon of red stems produced by P deff too fast. Sure that P deff often results on red stems, but its a reaction driven for other things thats stress plants too. I would try to confirm it by leaves showing signs of P deff aswell.

As far as I know, Ca and Mg dont interfere much with P. N, Fe, Mn does.

Your pic did me remember that I noticed that red stem at some point are relatively usual on LED grows. I need to ask people if they noticed it aswell, I dont know if its just me. I usually dont give it any importance if its only that, so I didnt asked it before.

 

[joe4444]

Your pic did me remember that I noticed that red stem at some point are relatively usual on LED grows. I need to ask people if they noticed it aswell, I dont know if its just me. I usually dont give it any importance if its only that, so I didnt asked it before.

I have looked at MANY threads about LED grows recently, and red stems do seem to be common. The plants look healthy otherwise, very healthy in most cases, with excellent bud production.

 

[guest456mpy]

As you can see, my nutrient problems are well behind me now.



I have had recurring red stems until 12/12 flip. I use 6:0:9 in .25 EC tap water @7.8 ph'd from ~6.3 to 5.8. 1/3 US Gallon per plant per day. In Floral stage I use same formulation + 1 tsp HG Koolbloom per US Gal. every 14 days. This is for 65 day strain. Top feeding to waste in 10" plastic pots using GH fine grade coco.

No problems what so ever. Very abundant harvest with thick full productive flower formation.

H.G.

 

[knna]

As you can see, my nutrient problems are well behind me now.



I have had recurring red stems until 12/12 flip. I use 6:0:9 in .25 EC tap water @7.8 ph'd from ~6.3 to 5.8. 1/3 US Gallon per plant per day. In Floral stage I use same formulation + 1 tsp HG Koolbloom per US Gal. every 14 days. This is for 65 day strain. Top feeding to waste in 10" plastic pots using GH fine grade coco.

No problems what so ever. Very abundant harvest with thick full productive flower formation.

H.G.

I love the first pic

I was refering to the nutrient profile that caused the problem, not the one working right. Sometimes, problems gives us the key, we learn more from mistakes than when doing right

 

[guest456mpy]

knna,
Totally agree on the nutrient profile of the bad grow. As I said, the nutrients were always my main suspect, but they themselves were undocumented. The entire DWC idea has been scrapped due to other more practical reasons, not performance.

Here's an update of pic 2 (current grow) to show bud development in 1 week.



H.G.