LED feed demands

[f-e]

GoatCheese
That aligns with the 15w per foot I was talking of. Being so high, it's probably like I get from 10-12w where I need to add mag as it's so low in my feed. It's not even given a numerical amount. It just says there is some. So is very low to escape the need to list it. Making my Mg problems unlikely to effect users of other feeds. Which likely puts you on the cusp of needing more food if you wish to use more light. What issues are you having. I expect Mg to be first, but that's just a generic answer. Yellow dry leaves you speak of. That would be interesting to see. Perhaps it's a combination of issues. I have had to buy N P K Ca and Epson in order to push individual things up&down when faced with a soup of problems. It's hard work... but rewarding

 

[GoatCheese]

I get about the same growth rate I got with my old lights before switching to cobs using the same amount of nutrients. The only thing I have added is the calmag.

In my bloom tent the growth rate and bud production is more or less the same as with my old cool tubed 250 watt Osram Plantastar HPS but with the three Cree cobs I get better light coverage into the tent. And in my veg cab I had 2 x 55 watt cfl light before. So I’m saving quite a lot of energy/money.

What I noticed since switching to cobs is that the resin production is better (larger resin glands) and the calyxes swell more in bloom. The buds look more like they would have been grown under 400w HPS light rather 250 watt hps, thou the bud size is more or less the same = tighter nuggets I guess.
..also my keepers that grow few nanners in late bloom, they start growing those nanners noticeably later under cobs compared to the hps light, so I’m quite happy that I switched to leds.


What isues am I getting?
Well, I don’t get the yellowing leaves any more since I learned to dim down the light but at first I fried them proper. Now the led bleach damage on the soil plants,esp. if they dry out, makes the leaves look slightly pale and they lose their waxy look; they develop sort of matte look, similar if the air is too dry and fans are aimed directly to the plants.

Here’s a photo of a plant in soil that dried out abit few days a go ..see the slightly pale matte look? This is one Cree COB @ around 23 watts + the 4000K 10 watt led flood light

Here's a photo is my G13Haze keeper in coco. I forgot I had another plant in coco also besides the auto, cause I normally grow in potting soil. It’s not so easy to see from the photo, but this plant in coco still has that healthy waxy look on her leaves. Same amount of nutrients and calmag, the only difference is the grow medium; soil vs hand watered coco, and in coco there’s much more moisture in the plants system so the leaves stay in better shape.

PS.

What a fukkin nightmare it is to use my picture callery on this new icmag platform!! ..i click one photo but it show me a completely different one ...aaaargh!

 

[ButterflyEffect]

Perhaps your P problem is in the 3 hours before bed and through the night. I'm not sure what you mean by watering them daily to flush, but it's a point of interest. I imagine the root system big enough to find food when fed, might not be big enough to find food in just water. While one big enough to find food it just water, might not like being fed. I would of thought this stressful for the plant. Could you mix the two buckets together and just give them that twice a day? Then if the run-off starts to leave the chart, put an extra feed through them about 20 minutes after a normal one. No plain water ever. That's for soil. Just another feed to replace the one that's there. Having given 20 mins for the salts to get dissolved as best as can be. My watering cycle is 9 mins, but is actually 5 on for near saturation, 10off, 4 on which is mostly causing run-off . Which gets a lot more out than 9 minutes straight. I do have quite a high runoff percentage but it's what keeps the root EC down, and refreshed. Though I'm aware K is a lot more soluble than Mg or Ca, though nothing like as soluble as N (on the whole). I'm not sure about P. I'm forever learning to.

My pic looks healthy at a glance and if they were long flowering plants okay. However this is them at 6 weeks during another run (I was unhappy with)
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I held N too high going into week 3 at about 165ppm. While I pushed the stretch and stature of them with P until that time, then lowered it way too much. Though still more than I would of used under sodium, by quite a margin. In line with my extra ppfd looking back. I need to really comb through my logs still, but this grow is over for me. Test done. I failed Which is the whole point of a test grow

Looks like quite the failure! It's good you're learning something along the way.

I thought plain water was a no-no in coco. What I mean by watering them daily to flush is that by the time they get to 8 hours into their day, the pots are getting a little dry. Not dry, dry, but needing a feed, or water, of some sort. That's the time that I give them water, figuring that it'll also flush to keep my runoff in check. What you're saying is maybe I should feed at half-strength both times? Would there be enough EC to fulfill their needs during the day? I only feed at 700ppm max.

Thanks for the advice, btw!

 

[chiesesganja]

try greenhouse biogrow~

I'm really starting to think that a water only soil recipe is going to be very difficult to achieve under LED. Especially if you have plants with a big appetite like I appear to.

I don't know. Maybe after 5 or 6 grows and constantly amending heavily and tailoring the cover crop you can achieve a water only recipe for heavy feeders. But from the get go requires a level of knowledge I have yet to acquire it appears.

Adding fish hydrolysate with kelp to my ACT may become a permanent addition anyways because of the huge increase in microbial activity I observed under my microscope. Tad Hussey and Microbeman are right - foam means nothing with ACTs.

 

[f-e]

GoatCheese
Yes the pics are screwed. I had to upload the 6 weeks bud shot again to show it. It's in my gallery, but just in name. If I share it, it's just a name. If I actually click the white space in my gallery where it should be, it does open in a new window though. I have sat here an hour trying to reply because I wanted to check another page first. A whole hour (actually just over) to navigate a few pages. Now I have to go and do something else.

I will be back

 

[f-e]

And back I am.
My mind turns to Mg and N while the books say sulfur. You could try Epson salts as a Mg+Sulfur fix, as it's magnesium sulfate. Higher in Sulfur than Mag.
I think it's N. It doesn't look like there is any gradient from top to bottom, but I still think so. I have had plants just like that using peat free organic composts whenever I have tried hardware store brands. Also a dose of N, especially organic is seems, will green up a plant and have it shiny in 24 hours. Urea could work in compost but is a bit slow in coco, then days later it peaks. It's just not usually got the biology of soil to convert it. As a third hint, your soil plant is worse. That same biological action uses up N, which isn't happening so much in the coco. Though I'm puzzled why you would feed the two the same.
Putting it together, your rejection of the idea LED users need more N could mean you're not trying it. There are quite a few clues here pointing towards N. As a 5th, that growth tip development could be seen with an N deficiency.
I have P on my mind, but only as coco feeds carry a lot less of it. Which makes me question the choice of one feed for two substrates. It's not thought of as causing this yellowing.


Joining some more dots up, it seems 15w per foot is a milestone. Sodium like growth and requirements. I just watched a migro video where he found 20w of 1.8umol/j created 400ppfd. 15w is obviously 25% less, but our leds could be 33% better to compensate for that. 2.4umol/j is a quite reasonable expectation and 400ppfd isn't so bad. 600ppfd might be great, but I don't see why 400ppfd can't see 1.3 grams per watt. Whaling the single gram of a HID. Using just 180w per meter. That sounds unbelievable but 180w x 2.5 = 450umol and a Top HID at 600 x 1.7 = 1000 but you loose so much it's painful. 650 might make it down, but them you have the heat issues and most importantly better morphology. It keeps getting closer to the truth. My 720w of decent LED's is just crazy, but I see gains to about 450w. Then I turn it up more and kill them all, but I have to try

 

[f-e]

ButterflyEffect
700ppm doesn't sound much really. Is that the 700 scale, making it about ec1.0 ?
I did a run at 1.0-1.1 which was what keeping the runoff at 1.5max called for. I was 25% under target. My target being what know I can achieve when I'm not trying something new. I couldn't do that once a day, then water it down, even if that wasn't too run-off.

The low P we spoke of has to be drip fed to waste every time, regularly. If not, then it's simply not there. It's been eaten.
I guess if P is your only concern, you could put some in that evening watering. I feel the plant would be happier with a more continuous diet though.

Stress training might involve dietary manipulation, but other than brushing the tops to limit stretch I don't practice anything like that. It's a bit like special teas. I don't practice voodoo, I'm saving up for my white smock

 

[GoatCheese]

And back I am.
My mind turns to Mg and N while the books say sulfur. You could try Epson salts as a Mg+Sulfur fix, as it's magnesium sulfate. Higher in Sulfur than Mag.
I think it's N. It doesn't look like there is any gradient from top to bottom, but I still think so. I have had plants just like that using peat free organic composts whenever I have tried hardware store brands. Also a dose of N, especially organic is seems, will green up a plant and have it shiny in 24 hours. Urea could work in compost but is a bit slow in coco, then days later it peaks. It's just not usually got the biology of soil to convert it. As a third hint, your soil plant is worse. That same biological action uses up N, which isn't happening so much in the coco. Though I'm puzzled why you would feed the two the same.
Putting it together, your rejection of the idea LED users need more N could mean you're not trying it. There are quite a few clues here pointing towards N. As a 5th, that growth tip development could be seen with an N deficiency.
I have P on my mind, but only as coco feeds carry a lot less of it. Which makes me question the choice of one feed for two substrates. It's not thought of as causing this yellowing.

Yea, I have Epsoms, I give some once in few weeks but I give the calmag with every nutrient feed.

The small plant in photo growing in soil, the soil dried out abit too much some days before I took the photo and that’s why the plant looks abit pale …I already explained this when I posted the photo. I posted the photo to show what happens when the plant dehydrates under modern leds, it’s what I have been talking about in my posts. As long as they don’t dry out or get too close to the COB they stay almost as healthy looking as the plants in coco, but go abit pale and dry looking as soon as the soil gets too dry.

When plants start running out of N the bottom leaves start yellowing and i get none of that, not on the plants in soil nor on the coco plants, so I don’t think it’s N deficiency.

There’s nothing wrong with the plant in coco, looks nice, healthy and green so why should I change something in the NPK feed?! I don’t read books, I try to read the plant
When the leaves dehydrate and start to go pale they also become dry/harsh feeling in my fingers. So to me the symptom is caused by dehydration because of led light bleaching (=Leds being too close to the canopy), not because of N deficiency. = bottom leaves on the plant stay green. They’re not yellowing at all which should be a sign of N being too low.

Feeding the plants too much N during bloom will make the bud smoke harsh, so I don’t want to pump up the N levels, cause I want smooth smokes. The bottom leaves on my blooming plants aren’t also fading/yellowing at all, so it isn’t N deficiency.

Even thou my plants get pale because of dehydrating under the COBs, they still get tip burn at the same time if I feed them too much nutrients, and they wouldn’t show nutrient burn if they actually would be needing stronger feeding, would they. Also the water leaves on my plants stay super green even thou the upper sun leaves are going pale abit from dehydrating, so to me that’s assign that they do get enough nutrients.

I have actually loweredmy nutrient strength with my blooming G13Haze this run, the one I have going in soil, cause I gave it too much BioBizz Grow/Nitrogen during the first time I flowered the cut.

Here’s a photo of my GHz during the first run, See the slight tip burn from too much N? So it can’t be N deficiency if you get tip burn. also note the water leaves being nice green color, thou the sun leaf looking abit dried out and pale but not too badly. It’s not lacking N.

You say I’m not trying enough with tinkering my NPK feed, but I think you could be tinkering with your feed too much and should start thinking about the led/cob bleaching as a dehydration damage rather than lack of nutrients.
Peace

 

[f-e]

I must be missing the point. I'm interested why you want to raise the lights further when only at 15w per foot.

What I'm hearing is you think it's the cobs fault you're not watering them enough. Obviously I'm missing something?

Why would you want the lights higher. What is the problem that's stopping you wanting more. 15w per foot is less than half what you could be using.

 

[GoatCheese]

I must be missing the point. I'm interested why you want to raise the lights further when only at 15w per foot.

What I'm hearing is you think it's the cobs fault you're not watering them enough. Obviously I'm missing something?

Why would you want the lights higher. What is the problem that's stopping you wanting more. 15w per foot is less than half what you could be using.

You grow in coco, right? There’s nothing wrong with my coco plants as I have stated many times, I even showed you a photo of one of them. Nothing’s wrong with it.
Watering plants in soil has it’s limits, coco growing is much more forgiving with over watering. When you grow in small pots of soil some times they dry out too much. I don’t even see leaves drooping from the soil getting abit too dry when the leaves are already going abit pale. Plants don’t behave this way under CFL lights nor under a small 75 watt MH bulb. , they can droop quite a lot from drying out without getting much leaf damage. Modern leds are different kind of animal.

You can see the nutrient burn from too much N in the GHz photo i just posted, can’t you. What point are you missing about that?

N defieincy shows as lower leaves turning yellow and I get none of that as I stated. What point are you missing about that?
How can i get nute burn from too much N, yet supposedly my sun leaves are yellowing because of lack of N at the same time? Get it??! Obviously it’s not possible.

The radiance from the cobs/leds need enough air (atmospheric gasses) between leds and the canopy to dissipate some of the energy out from the photons they’re emitting or the photons will dehydrate/fry the leaves when they hit them. That is why you need to have the light high enough. The radiance from modern cobs/leds is much more intense than from CFL of HPS lights.
If the cobs/leds are too close to the plants or you run the leds too hot, the leaves turn pale/yellowing, dry and brittle. It’s lack of moisture in plant tissue, not lack of N. What point are you missing about that?


You seem to stare at a ppfd meter and a calculator about what your light foot print should be instead of looking at your plants.
It’s not me being lost testing all kinds of different NPK ratios and whatever, it’s you. But if you want to over fertilize your plants because your light is running too hot cause you wanna max the output of your leds, then go ahead. I like smooth smoke, not over fed buds, and I will continue to adjust my cobs to suit my grow tent and enviroment without over feeding my plants or frying them. But you do whatever you wanna do.

I can grow plants with the same yields with 85-90 watts of COB light as I did with a 250 watt HPS. With my biggest yielding plant that’s about 2.5 grams/watt. I don’t feel I’m doing anything too wrong, my friend, or do you think that 2.5 grams/watt is not enough?

I have no interest in continuing this convo,sorry, I’m just too tired atm (I suffer from insomnia/bad sleep).
Peace

 

[Koondense]

"The radiance from the cobs/leds need enough air (atmospheric gasses) between leds and the canopy to dissipate some of the energy out from the photons they’re emitting or the photons will dehydrate/fry the leaves when they hit them."

This is not a valid explanation, maybe it's just missing IR in the spectrum. Colder leaves and high par make a bad combo. Otoh, i sometimes turn up my cobs and shine on the canopy with 37w/sqft and my plants can manage it with proper feeding and temperatures+humidity(vpd).

Cheers

 

[ButterflyEffect]

ButterflyEffect
700ppm doesn't sound much really. Is that the 700 scale, making it about ec1.0 ?
I did a run at 1.0-1.1 which was what keeping the runoff at 1.5max called for. I was 25% under target. My target being what know I can achieve when I'm not trying something new. I couldn't do that once a day, then water it down, even if that wasn't too run-off.

The low P we spoke of has to be drip fed to waste every time, regularly. If not, then it's simply not there. It's been eaten.
I guess if P is your only concern, you could put some in that evening watering. I feel the plant would be happier with a more continuous diet though.

Stress training might involve dietary manipulation, but other than brushing the tops to limit stretch I don't practice anything like that. It's a bit like special teas. I don't practice voodoo, I'm saving up for my white smock

As the clues start to come in, I'm seeing the runoff EC at, or just above input. In some rooms, the pH is down to 5.5-6, which is more in line with where it should be. I think you're right about the watering only. Osmotic shock maybe, so I'm designing the feed system to accommodate more frequent, but lower EC, fertigations. I run on the 500 scale, btw, so I'm around 1.2-1.3EC

 

[ButterflyEffect]

"The radiance from the cobs/leds need enough air (atmospheric gasses) between leds and the canopy to dissipate some of the energy out from the photons they’re emitting or the photons will dehydrate/fry the leaves when they hit them."

This is not a valid explanation, maybe it's just missing IR in the spectrum. Colder leaves and high par make a bad combo. Otoh, i sometimes turn up my cobs and shine on the canopy with 37w/sqft and my plants can manage it with proper feeding and temperatures+humidity(vpd).

Cheers

This was the theory that I came up with, although I don't use LEDs outside of hybrid T5s in Veg. I'm hesitant to make the switch in a 4 room perpetual environment where I'm running CMHs and the ROI would be less impressive compared to HPS.

It seems to me that in order to maximize Watts/SqFt, growers are moving the lamps close to the canopy trying to keep that DLI near 50W. Perhaps the local photosynthesis demands are too much given the lower transpiration levels. Maybe UV plays a part, too, I can't say.

For me, I'll stick with my rock-solid CMH setup until I get bored later this year and convert one of the rooms over.

 

[chilliwilli]

Hi folks had some yellowing after switch to bloom with my kingbrite lm301h+cree 660nm board(240w dimmed to 200) looked like fe deficiency for me.
the soil mix is a one year used notill water only. Had already some prob in veg under 150w cmh osram powerball hci-t 942 but thats because of the low n levels imo. Prayer pupil was very light green and grew slowly.
after i topdress a cup of a 50:50 kelp:shrimp mix everything looks better so far. Some tips are still yellow but everything is coming back to normal.

Overall temps are a little lower but not much. i let the temp rise to 31°c before the vent turns to 100%. But i can say for sure the plants drink way less.

 

[chilliwilli]

Hi folks i'm 2 1/2 weeks after flip and switch to qb leds.

 

[chilliwilli]

Since about a week its coming back. Already used some canna mg mono i had and the green color is coming back. The plants from clones show more sings of deficiency. The pic is 3chems

 

[DaveBowman]

Since about a week its coming back. Already used some canna mg mono i had and the green color is coming back. The plants from clones show more sings of deficiency. The pic is 3chems

What is your pH?

 

[chilliwilli]

Can't say. I grow in 90l container with no drainage so i can't check. Also i don't trust those soil ph meters so i have no.
The last runs had no problems.

 

[flylowgethigh]

Those single probe Ph meters work pretty well. When the soil is wet, conductive, and you have a lot of Cation Exchange Capacity, the meter goes crazy and moves straight to 4 or 5 Ph, in 6.7 soil and 6.5 water. I call it "sparking". I started a thread about in organic soil. I may be full of shit, but it is what I am observing.

 

[f-e]

I might try Mg from Epsom to see if it's the much forgotten sulfur. Doing so would also warrant some fe and could be applied as a foliage spray.

Have you depleted the N? I see leaf tips dying back and no fans. N doesn't always follow the classic bottom upwards, especially after the bottom has gone.

I would start with the spray as it's a quick answer.

Oddly I just had a crop wake up looking alarming yellow, but green up through the day. Day after day. As they filled the space the RH came up and it cleared. Below 50% was terrible. 55% wasn't satisfying. 60% fine. Though this was through transition so other things were going on.

I just can't get a humidifier during lockdown. I found whatever a sprayed on them greened them up though, even just water. I'm sure it was RH though a low pH can be interesting..