Plants not doing well with EB Gen 3 CRI90 4k strips

[Li_Mu_Bai]

This is in my veg room with recirculating coco system. My plants are showing signs of mag deficiency (see pics), and slow growth, and they start to droop about 4 hours before lights out on a 18/6 schedule. I've raised the lights and tuned them down to were they Lux is only about 10k (par conversion of about 250) at the canopy.

I've researched a ton, many other people new to LED are having similar problems. My theory is that these lights are too strong in the Blue spectrum.

Anybody have any input on this issue I would greatly appreciate it.

[TEKNIK]

Make sure your room temperature is right and sort out your nutrients. It has nothing to do with the spectrum

[Li_Mu_Bai]

Here's the thing. Prior to using these LEDs I used Ceramic Metal Halide with 4k bulbs and had none of the issues that I am having now. And I've read tons of threads on other forums of people complaining about similar issues. So, it definitely is the spectrum, or Spectral Power Distribution. There are no other different variables that I am dealing with.

I have raised my temps to 28c and my RH to about 68% and it definitely helped, very much actually. But I'm still having slow growth and drooping leaves after 14 hours of light, and this at a par of about 250.

Also, I have the EB Gen 3 CRI 90 3k lights for flower and they work great, healthy plants with no issues. In any case, if it is an issue of too much blue what can I do but buy another light, which is what I'm thinking about doing. I don't have the time to try and tweak my lights to get them back to what my previous light could do.

What can I do at this point other than change lights? Not much really. I would like to understand what the issue is but it is definitely complicated. How a particular configuration of the visible light spectrum effects marijuana plant growth is above my pay grade. I mean, these lights were not engineered for horticulture use, so who knows what the issue could be.

[TEKNIK]

Its definitely not the spectrum, intensity can be causing an issue but more likely your nutrients. Cal/mag is usually the cause. Im not the best with nutrients though. Not sure how many watts your old bulbs were but if you have reduced the wattage in half this can be causing an intensity issue. Reducing the wattage by about 1 third is the approximate saving you get with leds. I still feel its a nutrient issue though

[frankiezappa]

Same here. I'm running five eb gen 2 4k 56cm strips on a 120x60 cm,at the min amperage ,and i have to raise all the way up the light. I had slow growing and mag def. I have to spray them with a weak calmag solution...but it's definetely crap,slow growing. I have to drive them at minimum cause plants were heavily suffering and raise up at the max height the light(180 cm tent).

On the other tent i have 15 eb gen 2 3000k,fabric pots, air in out ,vent,in 100x90 cm ,some c02 from bags,very little feeding ...i have mag def if i just try to drive them more than 200watts at wall. the diy,is one i get from the blog here,very heavy and aluminum that i was thinking to drive at 300/400 watts.

I can't understand

[QuarterbackMo]

New to led’s here not new to growing at all I had the same issues under the cob light I just built so it’s not the strips but I recognize the symptoms for sure.

I’ve grown crazy healthy plants under all kinds of hid lights over the last 15 years give or take and the min I switched to the cob lights I built it was game over they turned to shit every single time but they always came out of it I just couldn’t figure out what was going on and like you guys said you turn the light down and or raise it up and boom everything is growing good again.

So here’s the thing I thought it may be the spectrum but I’ve got one set of bars with cxb3590 cobs and the rest all have citizen 1818’s and I’ve seen good grows with both so I knew it was something on my end.

Started adding 1/8 tsp epsom salt to correct the def and I’m back to solid the whole time with the lights blasting 100%.

I had both my soil less and soil plants get gnarly from going under the led I haven’t had a chance to see what the rdwc rooms do yet but that’s coming up they haven’t been swapped out from their de hps predecessors yet.

I personally think the spectrums drive the plants to use more magnesium for some reason myself idk why it is but that’s what cured my problem everything greened right up after that.

[TEKNIK]

New to led’s here not new to growing at all I had the same issues under the cob light I just built so it’s not the strips but I recognize the symptoms for sure.

I’ve grown crazy healthy plants under all kinds of hid lights over the last 15 years give or take and the min I switched to the cob lights I built it was game over they turned to shit every single time but they always came out of it I just couldn’t figure out what was going on and like you guys said you turn the light down and or raise it up and boom everything is growing good again.

So here’s the thing I thought it may be the spectrum but I’ve got one set of bars with cxb3590 cobs and the rest all have citizen 1818’s and I’ve seen good grows with both so I knew it was something on my end.

Started adding 1/8 tsp epsom salt to correct the def and I’m back to solid the whole time with the lights blasting 100%.

I had both my soil less and soil plants get gnarly from going under the led I haven’t had a chance to see what the rdwc rooms do yet but that’s coming up they haven’t been swapped out from their de hps predecessors yet.

I personally think the spectrums drive the plants to use more magnesium for some reason myself idk why it is but that’s what cured my problem everything greened right up after that.

Its to do with the leaf surface temperature, leds do not have the heat spike that HPS or CMH have, by not having that heat spike it effects the leaf surface temperature and you can end up with nutrient lockout. A bit of Cal/mag sorts it out. It depends on what nutrients you use also.

[ch4107]

It should be the right light height. I used eb gen3 90cri 3000K to bloom, and the effect was very good. I used a quantum meter to find the right light height.