What's the skinny on COB LED grow lights?

I'm looking for a replacement light for my 5'x5'x6.5' nursery tent. I previously had a spider farmer SF-4000 in there which was far too powerful for the space. I had to reduce the power to 50% to prevent light bleaching, but then the plants took off great. Much tighter node spacing versus my T-5 nurseries. I think a light in the 250-300W power range would be more than sufficient since I was operating the SF-4000 @ about 225W with great results. I've been checking out some COB grow lights on 'baba and they seem pretty sweet, but I notice not many people use them. I could see light spread potentially being a problem, but having never used one I'm only guessing. Are light bars and quantum boards the standard these days? COBS yesterday's news?
This is one of the COB units I was checking out: https://www.alibaba.com/product-detail/3500k-120W-240W-480W-red-blue_62477126863.html?spm=a2700.icbuShop.108120.4.2ddf7753bkWtuD It's a bit overpowered, but it looks like a great value for the money. I'm considering a quantum boad, a cob fixture, or a T5. I'm kinda leaning towards the Q board only because I was so impressed with the results once I dialed the power of the light in properly. They grow very bushy under the q board. The hydrofarm 8 lamp T5 I was going to order went from $168 to over $200 because of this fucking pandemic, and I refuse to overpay for ancient technology. At $168 it was an easy sell for me because I already have one in one of my nurseries and the plants really seem to love it in veg. They just don't grow as bushy. Now with the price being inflated substantially I figure I might as well get some new tech to play with. Here's a link to the Meijiu quantum board I'm looking at too: https://www.alibaba.com/product-detail/Meijiu-Led-Board-Best-Selling-QB_62090945327.html?spm=a2700.galleryofferlist.normal_offer.d_title.3f2e6d3fCHFGXU

I have the 480w version of the meiju in my pheno tent.
So far, it's been flawless and grows some incredible flower.
Although that fixture should generate a sufficient amount of photons to veg your 5x5, I think that you would get better results if you could split the fixture into 2 sections so that you'd get better uniformity.

After thinking about it for a moment, I'd use the meiju and cut the heatsink in half, drill a few new holes for hangers and use a bit of lamp cord for a jumper connection.
Should be cheaper than getting two separate 120w qb's.

i would just use the spider farmer on the lower settings, leds last a long time, but on reduced light output, they will last foreverish. a much longer time

OP, how do you view DIY?

As for the first light: not the right tool, you need good light spread. This means several fixtures or a very large, but not super powered light. This kinda of lights are a pita to ship and generally expensive and have more power than you need. Hence diy...

As for the first light: that kind of spectrum might be interesting for a nursery/clones/vegg situation but youd be better served by white leds, plus some supplementation strips. Id gor for a warm white + some blue on a separate dimmer. As you will be using lower intensity youre best served by adding blue as this is what controls stomata apperture/transpiration which can be a problem with low intensity led light when you cant afford to keep your space heated to 81F.

GBAUTO said:

After thinking about it for a moment, I'd use the meiju and cut the heatsink in half, drill a few new holes for hangers and use a bit of lamp cord for a jumper connection.
Should be cheaper than getting two separate 120w qb's.

Click to expand...

I don't want to get into cutting a board in half. If there were a warranty issue the merchant would not honor an exchange or repair in that condition. I like your idea of splitting the light output though. I have noticed the primary problem with quantum boards is light spread and hot spots. Rather than 1 big board it's best to have many small boards to spread the load. HLG seems to address this in some of their new fixtures. Lots of space in the frame that separates the boards to promote more even light spread and fewer hot spots. Great idea, but not $1300 worth of a great idea

It looks like I'll take a pass on COBS. Quantum boards seem to be the standard. Better light spread.

I was just scoping out some of the Meijiu lights again this morning to narrow down my shopping list, and it looks like all or most of their units have exposed wiring and electrical connections. Maybe I'm wrong, but I just looked at 3 separate models with exposed wiring. That's a deal breaker for me. How on earth can you safely spray IPM treatments on your ladies with exposed electrical connections? I had to look at the photos several times to verify what I was seeing. I'll probably order from the same vendor I ordered my last board from. I passed on Meijiu originally because of their 1 year warranty, and now that I see their boards are shipped with exposed wiring I completely understand why that is and I'm glad I took a pass. It's shocking that so many people recommend them with such shoddy workmanship. What's more perplexing is the wire guards they chose to omit from their boards are inexpensive. It's just one of those things that makes ya go, huh? Let me grab a link for the other board I'm thinking about. Had great service and the board was shipped with wire guards

Rocket Soul said:

OP, how do you view DIY?

As for the first light: not the right tool, you need good light spread. This means several fixtures or a very large, but not super powered light. This kinda of lights are a pita to ship and generally expensive and have more power than you need. Hence diy...

As for the first light: that kind of spectrum might be interesting for a nursery/clones/vegg situation but youd be better served by white leds, plus some supplementation strips. Id gor for a warm white + some blue on a separate dimmer. As you will be using lower intensity youre best served by adding blue as this is what controls stomata apperture/transpiration which can be a problem with low intensity led light when you cant afford to keep your space heated to 81F.

Click to expand...

Thanks for your insight Rocket Soul. I'm okay with DIY, but I would prefer to pay a bit more for an assembled unit. I have enough repair projects around the house and garden. I don't want a repair project showing up via UPS

I notice on 'baba there are many color options for the chips. 3000k, 3500k, 5000k. My veg T5 is 6500k and does a great job for vegetative growth, but I have not seen that rating available on any quantum boards. 5000k seems to be the max available. I'm planning to use these new lights for vegetative growth only. They will never be used for flowering. With that in mind should I shoot for a 5000k daylight spectrum to promote more vibrant vegetative growth?

I would prefer to buy 2 of these 110W units:
https://www.alibaba.com/product-detail/Good-quality-integrated-full-spectrum-ir_1600107919843.html?spm=a2700.icbuShop.41413.19.28f8d272kTNfki
Shipping is a deal killer though. To get 220W spread over 2 boards total cost with shipping = $213.40 - Far too expensive for 220W in my opinion.
Which brings me to my next option at 460w:
https://www.alibaba.com/product-detail/460w-farmer-sf4000-lm301b-v2-dimmable_62553903042.html?spm=a2700.wholesale.deiletai6.17.18f55ab3M7rnIy
The unit is overpowered for what I need, but the merchant rakes you through the coals on shipping for the smaller more ideal boards eliminating them as a viable option. This unit is $282 with shipping. It's about $80 over my planned budget, but seems to be the best option available for my needs. What do y'all think? Should I request a board with only 5000k spectrum since I'm using this for veg only?

This is also an option @ $163 for the 220W with both boards connected via heat sink. It doesn't spread the load as nicely, but I think it would adequately meet my needs for vegging in a 5'x5'. I think I'd feel better with the bigger 460w board above though for better light spread. Plus I can always dial that board up or down as needed. If the 220W was too low of power I'd have no option to turn up the power. I'd just have to buy another board and wait again for shipping etc. And it would cost more in the end.

The 5000k leaves some plants like a small little ball of leaves. 4000k is standard for veg. But some like 5000k for clones. i havent done led cloning so im not too sure.

Theres a led strip called the bridgelux vesta with 2 channel variable spectrum that i really like, that will do anything between 5000k and 2700k, dial in your stretch and node spacing perfectly. But maybe better waiting for the next gen, Vesta Thrive with fuller blue spectrum

Rocket Soul said:

The 5000k leaves some plants like a small little ball of leaves. 4000k is standard for veg. But some like 5000k for clones. i havent done led cloning so im not too sure.

Theres a led strip called the bridgelux vesta with 2 channel variable spectrum that i really like, that will do anything between 5000k and 2700k, dial in your stretch and node spacing perfectly. But maybe better waiting for the next gen, Vesta Thrive with fuller blue spectrum

Click to expand...

I was very happy with the vegetative growth the spider farmer unit produced which has a mixed spectrum. I'll have to dig into this whole 5000k spectrum quantum board thing a bit further today. I just can't help but think how happy my ladies are under 6500k high output T5 lighting. Wouldn't they respond similarly to a quantum board close to the same spectrum for vegetative growth? I believe the only reason the LED manufacturer's make the boards "mixed spectrum" is so the end user can use the lights from seed to harvest. However, if the end user is only using the light for 1 stage of growth that should change the formula a bit in what spectrum the light is producing. Need some LED gurus to chime in on this. My ship's taking on water and I need a life line here

Not a guru, but I've used various lighting to get my plants to a healthy state prior to moving to a flower tent. I found T5HO to be the most reliable with no issues of distance and gets every plant ready to dance. I use 6500k for 3 weeks, then move to a 3500k cobs/qb flower tent where I use cobs to isolate per plant and the qb as an overall addition.
Cobs definitely have a place in growing and I believe cobs add more 'beef' to the flower. You can almost see a cola grow when I add a diffuser to my 75w cob...quite intense and a plant has to be mature but, damn, it's a horse.
The mix gives me total control of each plant and its needs.

Oldreefer said:

Not a guru, but I've used various lighting to get my plants to a healthy state prior to moving to a flower tent. I found T5HO to be the most reliable with no issues of distance and gets every plant ready to dance. I use 6500k for 3 weeks, then move to a 3500k cobs/qb flower tent where I use cobs to isolate per plant and the qb as an overall addition.
Cobs definitely have a place in growing and I believe cobs add more 'beef' to the flower. You can almost see a cola grow when I add a diffuser to my 75w cob...quite intense and a plant has to be mature but, damn, it's a horse.
The mix gives me total control of each plant and its needs.

Click to expand...

Man I'm right there with you on your feelings about HO 6500K T5's. The plants just love the light. No burn and vivacious growth. Maybe I'm overthinking this and should just go with old reliable? I suppose it just chaps my ass the fuckers are increasing the price by $60 per unit just to screw people in a pandemic.

jonnynobody said:

I'm looking for a replacement light for my 5'x5'x6.5' nursery tent. I previously had a spider farmer SF-4000 in there which was far too powerful for the space. I had to reduce the power to 50% to prevent light bleaching, but then the plants took off great. Much tighter node spacing versus my T-5 nurseries. I think a light in the 250-300W power range would be more than sufficient since I was operating the SF-4000 @ about 225W with great results. I've been checking out some COB grow lights on 'baba and they seem pretty sweet, but I notice not many people use them. I could see light spread potentially being a problem, but having never used one I'm only guessing. Are light bars and quantum boards the standard these days? COBS yesterday's news?
This is one of the COB units I was checking out: https://www.alibaba.com/product-detail/3500k-120W-240W-480W-red-blue_62477126863.html?spm=a2700.icbuShop.108120.4.2ddf7753bkWtuD It's a bit overpowered, but it looks like a great value for the money. I'm considering a quantum boad, a cob fixture, or a T5. I'm kinda leaning towards the Q board only because I was so impressed with the results once I dialed the power of the light in properly. They grow very bushy under the q board. The hydrofarm 8 lamp T5 I was going to order went from $168 to over $200 because of this fucking pandemic, and I refuse to overpay for ancient technology. At $168 it was an easy sell for me because I already have one in one of my nurseries and the plants really seem to love it in veg. They just don't grow as bushy. Now with the price being inflated substantially I figure I might as well get some new tech to play with. Here's a link to the Meijiu quantum board I'm looking at too: https://www.alibaba.com/product-detail/Meijiu-Led-Board-Best-Selling-QB_62090945327.html?spm=a2700.galleryofferlist.normal_offer.d_title.3f2e6d3fCHFGXU

Click to expand...

Hi there we can offer you one sample for free if you would like to make a testing thread and grow journal for us, here is the link, we can send you money by paypal, then you can buy it for testing, what do you think ?

Timber makes COB grow lights that are really nice.

HortiBloom said:

Hi there we can offer you one sample for free if you would like to make a testing thread and grow journal for us, here is the link, we can send you money by paypal, then you can buy it for testing, what do you think ?

Click to expand...

If you are looking for other testers, I would be willing to put one to the test in one of my rooms, I have other COB LED's and HID lighting to compare the results to. Let me know as I am gonna be starting a run in a few weeks or so.

HortiBloom said:

Hi there we can offer you one sample for free if you would like to make a testing thread and grow journal for us, here is the link, we can send you money by paypal, then you can buy it for testing, what do you think ?

Amazon.com: Geyapex High PPFD Full Spectrum 400w Cree COB LED Grow Light with Veg and Bloom Switches for 4x4 Grow Tent: Home Improvement

Buy Geyapex High PPFD Full Spectrum 400w Cree COB LED Grow Light with Veg and Bloom Switches for 4x4 Grow Tent: Growing Lamps - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Click to expand...

I'd love to test one of those lights and journal the experience. It's actually perfect for the space I'm growing in. Feel free to PM me and we can make arrangements. Great looking light by the way!

Renfro said:

Timber makes COB grow lights that are really nice.

If you are looking for other testers, I would be willing to put one to the test in one of my rooms, I have other COB LED's and HID lighting to compare the results to. Let me know as I am gonna be starting a run in a few weeks or so.

Click to expand...

May I know what cob lights you're using please ?