Help me choose the right LED light

Hi bros!
I have a 40x40cm (15x15inch) growtent. I used to have a 250 watt cfl in a cool tube, but i feel like that isnt enough power. I usually have 4 autoflowers in 2 gallon pots or 1 regular cannabis plant in a 6 gallon pot.
What LED light would you guys recommend i use. The biggest concern is that my small grow tent is also verry short so the distance between the light and the tip of the plant can be 20cm (6 inches) maximum.
P.S. some links to actuall products would be verry welcome!

P.P.S. If you think that a different type of light would be better for my situation please do let me know.

I would say 2 small ( chinese ) quantumboards like 2 QB288 driven @ 70 Watts total would do great.
On that current you can hang them 15 to 20 CM´s to the plants canopy.
Maybe even 1 QB288 @ 70 watts can do it but you have to hang that a little higher.

Edit: This is 1 of the Alibaba respected sellers :
https://kingbriteled.en.alibaba.com/?spm=a2700.wholesale.cordpanyb.1.3d8a3b38T0ARYM

Or you can find the Chinese QB288 boards on aliexpress also.
Also check out the ´quantumboard´ and the chinese knockoff topic where you can read all the info you need if you decide to go quantum.

nederwierie said:

I would say 2 small ( chinese ) quantumboards like 2 QB288 driven @ 70 Watts total would do great.
On that current you can hang them 15 to 20 CM´s to the plants canopy.
Maybe even 1 QB288 @ 70 watts can do it but you have to hang that a little higher.

Edit: This is 1 of the Alibaba respected sellers :
https://kingbriteled.en.alibaba.com/?spm=a2700.wholesale.cordpanyb.1.3d8a3b38T0ARYM

Or you can find the Chinese QB288 boards on aliexpress also.
Also check out the ´quantumboard´ and the chinese knockoff topic where you can read all the info you need if you decide to go quantum.

Click to expand...

Thank you so much man!
I did some research on the quantumboards because i am still a newbie grower and i am not familliar with them. I dont know how to choose the right one, do you think this one would work fine for me? https://horticulturelightinggroup.com/collections/kits/products/135w-qb-v2-rspec-led-kit

Your total area is 40x40. 135 is just too much light. If i’m correct that comes out 1.7 square feet and with leds 50w per square foot is more than enough. Even 35w per square foot with qbs will give very good results. You need 75 max imo. 135, you will have to hang a lot higher. Not necessarily bad but you are limited heightwise.

In the setup you described i would stick with cfls tho. I see that high powered lights like leds are gonna do more harm than good for that setup. Just my 2 cents.

crimsonecho said:

Your total area is 40x40. 135 is just too much light. If i’m correct that comes out 1.7 square feet and with leds 50w per square foot is more than enough. Even 35w per square foot with qbs will give very good results. You need 75 max imo. 135, you will have to hang a lot higher. Not necessarily bad but you are limited heightwise.

In the setup you described i would stick with cfls tho. I see that high powered lights like leds are gonna do more harm than good for that setup. Just my 2 cents.

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Thanks dude!
Is it the same for all LED lights or just qb. I found this one on amazon and the dimensions are perfect and its really cheap. But i guess it is too strong as well? https://www.amazon.de/dp/B07Q7QB7KJ/ref=mp_s_a_1_22_sspa?keywords=pflanzenlampe&qid=1558029850&s=gateway&sr=8-22-spons&psc=1

crimsonecho said:

Your total area is 40x40. 135 is just too much light. If i’m correct that comes out 1.7 square feet and with leds 50w per square foot is more than enough. Even 35w per square foot with qbs will give very good results. You need 75 max imo. 135, you will have to hang a lot higher. Not necessarily bad but you are limited heightwise.

In the setup you described i would stick with cfls tho. I see that high powered lights like leds are gonna do more harm than good for th

Click to expand...

crimsonecho said:

Your total area is 40x40. 135 is just too much light. If i’m correct that comes out 1.7 square feet and with leds 50w per square foot is more than enough. Even 35w per square foot with qbs will give very good results. You need 75 max imo. 135, you will have to hang a lot higher. Not necessarily bad but you are limited heightwise.

In the setup you described i would stick with cfls tho. I see that high powered lights like leds are gonna do more harm than good for that setup. Just my 2 cents.

Click to expand...

The problem i have with cfl is that only a third of the grow tent gets enough light because of the shape of the light bulb. In fact the two plants in the back (on the picture they are below the terrible area) barely have a few white hairs while the ones in the good area are already in full flower showing like week 5 stage of flower. thats why i am thinking of led because the light will be nicely distributed.
I will attach photos so you can understand my issue with the cfl

crimsonecho said:

Your total area is 40x40. 135 is just too much light. If i’m correct that comes out 1.7 square feet and with leds 50w per square foot is more than enough. Even 35w per square foot with qbs will give very good results. You need 75 max imo. 135, you will have to hang a lot higher. Not necessarily bad but you are limited heightwise.

In the setup you described i would stick with cfls tho. I see that high powered lights like leds are gonna do more harm than good for that setup. Just my 2 cents.

Click to expand...

I am sorry for spamming bro but i think I found the perfect one. What do you think?
https://www.ledgrowshop.eu/unit-farm/ufo-lite-100-led-grow-lights/
It says in the description it is for 1.7*1.7 coverage in flower.

The problem is that you really don’t have the vertical space to utilize leds in my opinion. The second fixture you posted suggests 12”-18” height for flower. You have 1/2 to 1/3 of that vertical space. Plants will suffer. The top leaves will get oversaturated with light and the top buds. This will cause bleaching.

You really need something you can dim if you want to switch to leds. One of those quantum boards with a dimmer should serve well but i don’t know the dimensions of those. If you can fit 2 in there and run them at 30 watts each. Thats plenty of light and you’ll get better results imo. Even that may be too much.

This wattage stuff is just a general baseline to calculate. All leds are different and even in the same led family, top bins diodes could have more than 10-15% output increase and the colder you are able to run them more light they are able to emit at the same wattage.

In you case seeing you’ll keep them extremely close, even 1 board run at 40 could give you very good results. Cfls and leds are very different in the efficiency department. I know that sound very low. Going from 250 to 40 but leds are incredibly efficient compared to cfls.

Now i must say i have never done a micro grow like yours but i keep my leds at least 35cm at all times. These are powerful lights.

Cannabisnt said:

Thank you so much man!
I did some research on the quantumboards because i am still a newbie grower and i am not familliar with them. I dont know how to choose the right one, do you think this one would work fine for me? https://horticulturelightinggroup.com/collections/kits/products/135w-qb-v2-rspec-led-kit

Click to expand...

That is an awesome light and it´s dimmable with the onboard voltage / Ampere dimmer on the driver.
With that Meanwell driver ´ A ´ type you can dim it to around 50 % which would be around 65 Watts.
The problem is the height of your tent , if it´s only 20 CM max the light to canopy then you can get problems when the plants grows higher then that.
But with 2 of that same boards on that driver @65 /70 Watts you can hang them above the canopy at 15/20 CM with no problem.
65/70 Watts is even a bit to much for a space of 40x40 CM = 0.16 M2 , but it´s doable .
HLG is on this moment a real good choise for quality products so if you can afford the price choose HLG .
Keep reading the quantum boards topics , which can take hours and days , then decide what you buy.
But 2 of that HLG 288 boards @ 65 /70 Watts would do a great job at that little height in the tent.
The more boards the better in small space growrooms since the height that you can lower with more boards .
Only problem is that HLG on their websites states that the heatsink is 340 MM ( 34 CM ) , but what is the bredth ? That could be not much more then around 19 CM because of the size of the tent itself.
The chinese qb288 is around 28 x 17 CM so 2 of that boards with an same size heatsink would fit in 40x40 CM.

Edit : Try that blurple light in post 6 and waste time on vintage led tech from about 10 years old.
Don´t make that waste of money and time because there are so much better Leds in this time that there is no reason to don´t use them.
Just a lesson which many beginners on the ledgrowing have to overcome, just skip that lesson.

nederwierie said:

That is an awesome light and it´s dimmable with the onboard voltage / Ampere dimmer on the driver.
With that Meanwell driver ´ A ´ type you can dim it to around 50 % which would be around 65 Watts.
The problem is the height of your tent , if it´s only 20 CM max the light to canopy then you can get problems when the plants grows higher then that.
But with 2 of that same boards on that driver @65 /70 Watts you can hang them above the canopy at 15/20 CM with no problem.
65/70 Watts is even a bit to much for a space of 40x40 CM = 0.16 M2 , but it´s doable .
HLG is on this moment a real good choise for quality products so if you can afford the price choose HLG .
Keep reading the quantum boards topics , which can take hours and days , then decide what you buy.
But 2 of that HLG 288 boards @ 65 /70 Watts would do a great job at that little height in the tent.
The more boards the better in small space growrooms since the height that you can lower with more boards .
Only problem is that HLG on their websites states that the heatsink is 340 MM ( 34 CM ) , but what is the bredth ? That could be not much more then around 19 CM because of the size of the tent itself.
The chinese qb288 is around 28 x 17 CM so 2 of that boards with an same size heatsink would fit in 40x40 CM.

Edit : Try that blurple light in post 6 and waste time on vintage led tech from about 10 years old.
Don´t make that waste of money and time because there are so much better Leds in this time that there is no reason to don´t use them.
Just a lesson which many beginners on the ledgrowing have to overcome, just skip that lesson.

Click to expand...

Thanks for the quality advice!
btw did you mean this one when you were talking about post 6
https://www.ledgrowshop.eu/unit-farm/ufo-lite-100-led-grow-lights/

Cannabisnt said:

Thanks for the quality advice!
btw did you mean this one when you were talking about post 6
https://www.ledgrowshop.eu/unit-farm/ufo-lite-100-led-grow-lights/

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That´s the one i talked about. Many beginners make that same mistake with that kind of ´ Vintage ´ lights , mostly the Purple light ( Blurples as some call them now )
Then they grow with it and get problems with the grow and sometimes make even more mistakes if they don´t realise the lamp is the problem .
Some even give up on growing and think they can´t grow , or they buy an modern quality ledlight and then begin to realise they had buy that at the first step.
Many beginners make that mistakes, lots of stories on the growforums about that mistake.
But the Quantumboards are a different story , some experienced growers grow per watt 2.5 Gram Cannabis , thats around 5 times more then the Vintage purple leds do and did 10 years ago.
So to safe that time you are OK with the quality stuff from the beginning.

As an example, that light in that link says the power is 105 watts and give 4119 Lumen,
which is 39 Lumens per watt .
Even an normal house ledbulb can give around 90 Lumens per Watt so thats more then 2 times more of that Purple ufo light, just a thought.

The HLG quantumboard in the other link use the ´ Samsung LM301B ´ chips, which are rated up to 180 Lumens per watt, so thats more then 4 times more Lumens and close to even 5 times more Lumens.
Also the lifetime of the Samsung chips goes up to 50.000 Hours and the meanwell drivers have a warranty of 7 ( ! ) years, that´s real quality and real good value for your money.
So yes the HLG quantums kits are a very good choise and installation is real simple .

Check out this topic about the HLG lights to learn more about this quantumboards.
https://www.rollitup.org/t/diy-with-quantum-boards.927159/