Trouble adjusting to COBs

[tatikas]

Hey all!
Has anyone else had a hard time adjusting from HPS to COB LEDs? I was doing relatively well before but the plants either don't seem to like the LEDs too much or it's just bad luck or something.
Everyone seems to add some cal/mag after switching to COBs, my tap water should have plenty of calcium, so I've been adding some epsom salts and they do look kinda mag def but it really hasn't solved the issue.
The plants seem to grow slower and just generally look kinda unhappy, pale and droopy. They kinda look like they need more of something but that could always be a sign of a lockout I guess. I've always used the same nute (Canna&Hesi) and watering schedule and it has worked well with the HPS. They started having issues already in the beginning, two different strains.
I measured the light with a lux meter and the LEDs give about the same intensity of light in the whole area as the HPS did right beneath it so I don't think it's too much, plus I dimmed it down a little.
I've also tried to raise the tempreture considerably, from ~21C to ~28C and it hasn't helped either.
So all of ya'll.. what have you had to change or adjust after the switch to COBs? Less or more nutes? Something else??

 

[Rusher]

You didn't mention the temperature of the COBs you're using. I'm using the 3500K Vero29s, and the only thing I had to add was CalMag, lots of it. Easy transition from HPS to COBs for me. Plants look as good, if not better than under HPS.

Best of luck finding your issue.

Cheers!

 

[ANC]

I'm going to give you the secret, add about 10 to 15% vermicompost to your coco.
Also, you are going to have to cut a leaf and go look at it in normal light, the leaves tend to look worse than they are under the LEDs in this respect.
After a week or so, your leaves should go green and waxy again, try to feed minimum ppms to kill off as few as possible of the bacteria in there the first few days.
You can honestly water with just pHed water a few times, they vermicompost will dilute into the water and it won't shock the plants like plain water on coco does normally.

You will come back and thank me later.... I played up and down the ppm chart with calmag plus and epsom salts and fuck knows what.... the easy answer with the best result, add vermicompost.

 

[tatikas]

You didn't mention the temperature of the COBs you're using. I'm using the 3500K Vero29s, and the only thing I had to add was CalMag, lots of it. Easy transition from HPS to COBs for me. Plants look as good, if not better than under HPS.

Best of luck finding your issue.

Cheers!

Thanks for your reply. I use 3500k Citizen 1212s. I've been reluctant to buy cal/mag since I have pretty hard tap water and most of that hardness is calcium AFAIK.
By lots of it you mean with every feed/watering?

 

[tatikas]

I'm going to give you the secret, add about 10 to 15% vermicompost to your coco.
Also, you are going to have to cut a leaf and go look at it in normal light, the leaves tend to look worse than they are under the LEDs in this respect.
After a week or so, your leaves should go green and waxy again, try to feed minimum ppms to kill off as few as possible of the bacteria in there the first few days.
You can honestly water with just pHed water a few times, they vermicompost will dilute into the water and it won't shock the plants like plain water on coco does normally.

You will come back and thank me later.... I played up and down the ppm chart with calmag plus and epsom salts and fuck knows what.... the easy answer with the best result, add vermicompost.

Should have mentioned it before... I use soil.. would that change anything?

 

[coreywebster]

In all honesty I haven't had to adjust anything and I don't have to had cal/mag either.
When I switched to QBs I had to find the right height to not fuck up my plants, didn't have much of a problem with the cobs, been a bit less aggressive.
Plants love both lights and sit all perky until harvest.

 

[Rusher]

Thanks for your reply. I use 3500k Citizen 1212s. I've been reluctant to buy cal/mag since I have pretty hard tap water and most of that hardness is calcium AFAIK.
By lots of it you mean with every feed/watering?

CalMag isn't just Calcium and Magnesium; it also a bunch of micro-nutrients your tap-water probably doesn't have.

And the girls under COB get CalMag every other water/feed.

 

[coreywebster]

Only a thought but if your starting seeds or small clones under Cobs then maybe the frequency of watering (staying the same as you did with HPS) has screwed up your roots. Overwatering causing problems that you never recovered from.

 

[ANC]

Don't use salts on your soil mate.
With soil there is the issue that it really needs to be properly aged... for me that is about 300 days after which you give it another light fertilizing with green manure, biochar and organic fertilizer. All this while you never leave the surface without things growing on top. The more species the better.

There is also the chance that you have nematodes or that the soil in the pots just do not heat up sufficiently. This knocks out ammonia reducing bacteria but not urea reducing bacteria that makes ammonia...

 

[diyled]

Most of the time its not a food issue. Or anything to do with calmag...

Are the lights to close? And You say 21C, is that root temps? They will be a few degrees lower if its 21C air temps.
How many days since you got the temps up? They could just be recovering from the cold.

Just guessing without some pics in natural light.

 

[tatikas]

I wouldn't say that they were in the "cold" before, I just raised the tempreture since that's what everyone seems to suggest for LEDs. I'm too paranoid to post any pictures tbh, i live under a nazi goverment as far as drugs are concerned .
From what i've gathered they mostly look mag def, plus the leaves kinda cup downwards lenghtwise, opposite of cupping upwards because of heat stress. Some leaves kinda have "the claw" as in nitro tox but without the dark green colour.
Recently i repotted for the second time and they kinda looked rootbound. But they were definitely not rootbound during the previous repotting, yet had the same symptoms. I'll probably restrain from any additional nutes for a while since the soil a use has nutes for a good couple of weeks at least.

 

[Randomblame]

How much watts per sft.? It sound like too much intensity also known as bleaching.
Is the yellowing on the upper leaves and the leaves below the canopy stay intact?
At which current the COB's are driven?
How much distance between COB's and canopy?
Way too less info for an adequat answer, mate.
Dimm the light further or rise the whole lamp a few inches. Reduce the light below 30.000lx until they recover, than rise it slowly to 50klx, not more! Temps should be at least 25°, better 28°C, 18°C at night in okay. Plants should use the same amount of water as with HPS.
Maybe you should consider switching to a hydrosystem. Coco drain-to-waste systems work very well with LEDs, as the plants in a hydro system can uptake more nutrients.
Plants under LED have much more nutrient requirements.. It's not only cal/mag.

If the overexposed leaves are already starting to wither (upper half of the plant is yellow), forget them and put on a few new gals. Watch out for 16-24" spacing next time and slowly increase the intensity but not more than the plants can handle.
Remember, 60klx is about 900μmol/s/m² (a bit less), which is close to the maximum without additional CO². Have had the same issues with soil using 400w of COB's in a 2x 4' tent 12" above the canopy and dimming to 320w helps a lot.
For plants in soil I recommend 500-700μMol/s, in soilless media up to 900μMol/s without CO². Above a certain intensity it's difficult to feed the plants adequately, especially in soil. Vermi- and ripe garden-compost provide a large amount of nutrients over a long time and liven up the soil with beneficial microorganisms, which are neccessary. You can add both to your soil without letting it ripen for a long time, it's imo only needed if you add powdered bio-fertilizers like blood- or bone-meal, which need soil living bacteria to make it usable for the plants.

 

[boostedhonda]

When u switch from hps to led it can be a big adjustment. The biggest thing is temp. Hps emits infrared with increases the leaf surface temp, so u want to keep your temps around 78. when u use led there is no infrared, so u are not able to achieve the same leaf surface temp. so ideal temps are in the 80-85 degree range. You also have to keep in mind that with led the plants will not transpire as much, meaning u will need to increase the strength of your nutrient solution and decrease the frequency of watering. let the pots get nice and light before u water

 

[InTheValley]

When u switch from hps to led it can be a big adjustment. The biggest thing is temp. Hps emits infrared with increases the leaf surface temp, so u want to keep your temps around 78. when u use led there is no infrared, so u are not able to achieve the same leaf surface temp. so ideal temps are in the 80-85 degree range. You also have to keep in mind that with led the plants will not transpire as much, meaning u will need to increase the strength of your nutrient solution and decrease the frequency of watering. let the pots get nice and light before u water

WOW, interesting. Here I thought LED in general temps around 83 because no IR, so i keep my temps up around 81F. BUT, my light does have IR, ( perfect Sun BlackDiamond) so I guess I should be around 77 or so??

No wonder they look like they mutated, lol

 

[cookie master]

mine mutate too, I think its because led stinks.

 

[boostedhonda]

24-36” high in veg and 8-12” in flower is what I run in flower. Let’s agree to disagree cookiemaster. There is no comparison to the quality of led grown to hps grown imo

 

[Humple]

mine mutate too, I think its because led stinks.

Either you haven't taken the time to read the COB/QB/strip grow journals around here, or you choose to disregard their amazing results.

 

[cookie master]

its a light, it should grow plants. Theres a ton of fakes who are selling the products and I can say that a t8 works better than cobs for me. I really thought this gen was the one where they surpassed hps but my results are dismal. Its failed every time I try vegging. The plants barely grow and turn all ruffly and purple in veg.
I wanted it to work and then I planned on building them, but I cant sella product I dont believe in.

 

[boostedhonda]

I’ve had the same problem. Stems turn purple, leaves look pale and ruffled and the leaves droop. It was because of less than optimal temps. I raised my nutrient concentration a bit and put an oscillating fan on them on high to help the pots dry out quicker and overnight they looked much better

 

[nfhiggs]

its a light, it should grow plants. Theres a ton of fakes who are selling the products and I can say that a t8 works better than cobs for me. I really thought this gen was the one where they surpassed hps but my results are dismal. Its failed every time I try vegging. The plants barely grow and turn all ruffly and purple in veg.
I wanted it to work and then I planned on building them, but I cant sella product I dont believe in.

Too many people having great success for it to be the light. You just need to figure out what adjustments to make in your process.