Mixed spectrum COBs

[Nugachino]

Hey Rollers.

I've got a question for you lot.

I'm thinking about building one of Cutter's Cree based Growmau5 kits. And I was wondering if it's feasible to go with a quad spectrum setup. As in 1x 6500k, 1x 5000k, 1x 3500k & 1x 2700k COB. That way I'm covering more bases.

Or. Would I be better off choosing two of those four chips and just doing two of those instead?

I really don't know what option to choose. My last light was a 90w GrowSmart: GS-135. A blurple light with extra LEDs around it.

The tent I intend to put it in is 1.98ft x 1.98ft x 5.57ft. And the light is 200w with dimmer function.

Cheers in advance for any help offered.

 

[Olive Drab Green]

I think you'd do yourself better sticking with the 3500k spectrum, although the 3000k and 4000k are close enough. 80 or 90 CRI. Best PPFD.

Just my two pesos.

 

[Nugachino]

Why no blue spectrum Olive? Just curious

 

[Olive Drab Green]

Why no blue spectrum Olive? Just curious

It isn't really necessary. You want a good white spectrum that peaks naturally in reds and blues. And I believe the reds are slightly more weighted, PPFD wise. 3000-4000k will take you all the way through, veg to bloom to harvest. I prefer the 3500k and I could be wrong, but I believe it's what most people are using, followed by 3000k or 4000k.

 

[Olive Drab Green]

Not necessarily saying it wouldn't work, I just want to see you achieve the best PPFD for best growth. I, personally, have no experience using higher Kelvin chips.

 

[Nugachino]

Hm ok. I don't really understand the ppfd thing. I just know that plants respond to certain red and blue spectrums more so than say violet or green light.

I'm still trying to absorb all this information on growing indoors.

Thank you for your input though. I'm glad someone knows what I'm trying to do.

 

[Stephenj37826]

Honestly I think you would be very pleased with 3500k 90cri. Running different kelvin cobs you will end up with uneven color mixing.

 

[Olive Drab Green]

For PPFD (Photosynthetic Photon Flux Density, typically measured in micromols per square meter) you want to aim as close to 1200 as possible. 1200 is the optimal amount of light a plant can use. At 1500, your plant will actually start to experience photoinhibition and potentially cellular destruction. A 600w HPS typically puts out 1000-1200 PPFD. A 1000w HPS, ~2100 PPFD.

 

[Olive Drab Green]

Honestly I think you would be very pleased with 3500k 90cri. Running different kelvin cobs you will end up with uneven color mixing.

I run two 80 CRI 3500k Cree CXB3590s (one on each end) at 2150mA, and in between them, I run a seventh gen Vero29C in 3500k 90 CRI at 1670mA.

 

[Nugachino]

I've heard that the 90% CRI chips aren't as effective as the 70 and 80% ones are. Is there any truth to this?

 

[Nenno44]

I just added some 2700k 90cri to my 3500k 80cri during this currently finishing grow and I am pleased with the outcome.

 

[Olive Drab Green]

90 CRI puts out more PPFD, but also a bit more IR, and I think someone said the plants stretch a little more under it? In any case, I like the higher PPFD, and I haven't experienced any unreasonable stretch.

 

[Nenno44]

on this grow i turned the 90cri and 730's on after the stretch was done. on the next grow im going to turn the 90cri on from day one of 12/12 and see what the stretch is like for myself

 

[Nugachino]

Okay. How about if I mixed the 6500k and 3500k chips? I really don't want plants getting all that tall. Though hopefully these next ones end up larger than my current 15cm midget I have going.

 

[Nugachino]

I'm not dismissing just going straight 3500k. Just that I've heard plants stretch more under red spectrum light than if subjected to about 30% blue too.

 

[Nugachino]

Honestly I think you would be very pleased with 3500k 90cri. Running different kelvin cobs you will end up with uneven color mixing.

So. How does the mixing of kelvins affect the plants? I thought they needed to be exposed to different spectrum for best results...

 

[Stephenj37826]

I can tell you from customer feedback that intensity has as much or more to do with internodal spacing as CCT. In the case of the Maximizer I have several users that say they had to dim it down so the plants would grow up......
I have observed similar results.

 

[Stephenj37826]

Also I'm not a big believer in changing spectrums as the plant has to adapt each time. So you are essentially slowing them down when you do. Look at 3500k 90cri citizen. It has alot of blue.

 

[Nugachino]

Maximiser?

 

[Olive Drab Green]

I can tell you from customer feedback that intensity has as much or more to do with internodal spacing as CCT. In the case of the Maximizer I have several users that say they had to dim it down so the plants would grow up......
I have observed similar results.

Agreed. I didn't dim, though. I kept my shit tight.

Maximiser?

Their deluxe model.