COB suggestions for a small veg/propagation tent

V

velvet_underground

Member
I'm looking to eventually set up a small tent for seedlings, mothers and cuttings approx. 3'W x 2'D x 3'H.

Would 2 or 3 COBs work better in this space and what color temp is preferable? 5000k, 5700k or 6500k?

I'm thinking about driving them with a 185W LED dimmable driver.

Thanks!
 
Evil-Mobo

Evil-Mobo

Well-Known Member
These blanket kelvin recommendations need to come with brand of COB as well now IMO as the charts are not the same across the different brands when comparing similar kelvin ratings.

OP- with the dimensions you give I'd go 5K on Cree or 6500K Citi and run the cobs bare. Unless you think you might ever flower but this seems like a mom/veg space from your post.
 
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Trippyness

Trippyness

Well-Known Member
Evil-Mobo said:
These blanket kelvin recommendations need to come with brand of COB as well now IMO as the charts are not the same across the different brands when comparing similar kelvin ratings.

OP- with the dimensions you give I'd go 5K on Cree or 6500K Citi and run the cobs bare. Unless you think you might ever flower bit this seems like a mom/veg space from your post.
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Agreed, I would assume OP would look at charts. Running bare for Veg is best for sure.
I just glanced at his dimentions your correct a higher CCT would be best due to low high restrictions.
@Evil-Mobo is correct.
 
freemanjack

freemanjack

Well-Known Member
Luxeon 1211 or 1205 work well for veg and are hugely efficient, as to cri we have yet to see any improvement with higher cri cob's of the same wattage and have gone back to using 70cri for most applications as they are usually more lum/w that the 8-90cri equivalents, we have also used under-driven vero 29's with great success too. As to kelvin numbers, we are now using mixed arrays of 2700k and 4000k for both veg and flower as the plants seem to love the peaks on a and b chlorophyll wavelengths and there are no cobs that efficiently deliver on both. A mate has the greenest healthy girls in a 4 x 6 running 120w into 6 luxeon 1211's @ 2,7k & 4,k
 
freemanjack

freemanjack

Well-Known Member
VegasWinner said:
I like what @Trippyness says, I use a mix of 3500/5000k peace
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nice choice for veg, think I might have opted for 3k or 2,7k just to get those peaks right over the 400nm and 660nm but is small diff really as the higher k will have better lum/w so total number of angry pixies hittin the canopy is probably about equivalent.
 
Evil-Mobo

Evil-Mobo

Well-Known Member
velvet_underground said:
Thank guys.. Evil-Mobo, you are correct, this would only be for a small mother / veg space (never flower). I would have never thought to run them bare, great suggestion.
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This is my opinion from my research and what I am seeing so far in my own veg tent and the flower setup that is currently vegging a big sick plant as well.

These plants respond well to less current per COB (driven softer) and put closer to the canopy......running them bare like this for veg gives a nice spread and is a good combo with the softies.

Then you have the opposite end of the spectrum. Run them hard as all get out and put them up higher with good optics. I figure the guys building lights have done a bunch of R&D so there's really no wheel to re-invent here right now.

I just took down the window venting for my portable A/C that's how much of a difference the COB's are making in my room. I live in a hot and tropical environment too so no winter snow fall colors etc here.

Your head can spin man but the good thing is when you do DIY if it doesn't please you change it. Or just run different setups and test them yourself.

There's just so many different variables that need to be taken into consideration and often are not is all. We need to help people get back on track growing some dank ass plants and stop arguing over a percent or two in efficiency that is all within the margin of error of any tests.

I myself am trying a certain HID mentality if you will with my K temps/color choices. For HID was Blue MH for veg then HPS for flower (ie: RED) So I chose 5K for my veg tent and 3K for my flower setups. I will aslo test in the future some plants beginning to end under each as I am told the 3K has "different" growth characteristics.

However, my quest is also different than most. One part no one really talks about is cost effectiveness. So I set out to build an LED that was on par cost wise to my platinum 1K ballast and bulbs for my Eye Hortilux HID's. IF I have to spend more and run watt for watt I do not see the advantage for me as a "home grower" aside from the heat and less noise etc. BUT, I can always hang more lights if I need to as well and it spreads the cost right?

Sorry just my $0.02 and rant over. I am no expert and have made many errors as a new grower but try to learn from everything. This was my second DIY light, and if it keeps going as it is there might not be anymore HID here in the MOBO garden.

You need to have a solid plan going in or you will just amass a pile of parts as you change your mind (ask me how I know) lol.........

Keep us posted I want to see this running and growing plants
Cheers! :bigjoint:
 
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freemanjack

freemanjack

Well-Known Member
Evil-Mobo said:
This is my opinion from my research and what I am seeing so far in my own veg tent and the flower setup that is currently vegging a big sick plant as well.

These plants respond well to less current per COB (driven softer) and put closer to the canopy......running them bare like this for veg gives a nice spread and is a good combo with the softies.

Then you have the opposite end of the spectrum. Run them hard as all get out and put them up higher with good optics. I figure the guys building lights have done a bunch of R&D so there's really no wheel to re-invent here right now.

I just took down the window venting for my portable A/C that's how much of a difference the COB's are making in my room. I live in a hot and tropical environment too so no winter snow fall colors etc here.

Your head can spin man but the good thing is when you do DIY if it doesn't please you change it. Or just run different setups and test them yourself.

There's just so many different variables that need to be taken into consideration and often are not is all. We need to help people get back on track growing some dank ass plants and stop arguing over a percent or two in efficiency that is all within the margin of error of any tests.

I myself am trying a certain HID mentality if you will with my K temps/color choices. For HID was Blue MH for veg then HPS for flower (ie: RED) So I chose 5K for my veg tent and 3K for my flower setups. I will aslo test in the future some plants beginning to end under each as I am told the 3K has "different" growth characteristics.

However, my quest is also different than most. One part no one really talks about is cost effectiveness. So I set out to build an LED that was on par cost wise to my platinum 1K ballast and bulbs for my Eye Hortilux HID's. IF I have to spend more and run watt for watt I do not see the advantage for me as a "home grower" aside from the heat and less noise etc. BUT, I can always hang more lights if I need to as well and it spreads the cost right?

Sorry just my $0.02 and rant over. I am no expert and have made many errors as a new grower but try to learn from everything. This was my second DIY light, and if it keeps going as it is there might not be anymore HID here in the MOBO garden.

You need to have a solid plan going in or you will just amass a pile of parts as you change your mind (ask me how I know) lol.........

Keep us posted I want to see this running and growing plants
Cheers! :bigjoint:
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Is very tentative as yet (nothing remotely conclusive) but it appears that higher k values provoke longer internodals and lower values shorter nodes, hence going as low as 2,7k even for veg. Worth noting that with k values the blue end may be more luminously efficient on paper but more, lower energy, photons are emitted per watt from red spectrum than blue, it seems to kinda average out so plant morphology (shape) becomes the determining factor.
 
Evil-Mobo

Evil-Mobo

Well-Known Member
freemanjack said:
Is very tentative as yet (nothing remotely conclusive) but it appears that higher k values provoke longer internodals and lower values shorter nodes, hence going as low as 2,7k even for veg. Worth noting that with k values the blue end may be more luminously efficient on paper but more, lower energy, photons are emitted per watt from red spectrum than blue, it seems to kinda average out so plant morphology (shape) becomes the determining factor.
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I might be confused here but I think you have this backwards?

The 5000K up have more blue which is what causes shorter growth and the 3000K has more red for more stretch? What am I missing?
 
freemanjack

freemanjack

Well-Known Member
Evil-Mobo said:
I might be confused here but I think you have this backwards?

The 5000K up have more blue which is what causes shorter growth and the 3000K has more red for more stretch? What am I missing?
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Doh! i'm arse upwards, gotta stop hittin this hgk so hard first thing in the mornin, my apologies fellas I stand duly corrected on my stumblefuckery, but the photon shit is right way up, blue = high energy/fewer photons, red = lower energy but more photons.
 
Rahz

Rahz

Well-Known Member
velvet_underground said:
Interesting.. I was under the assumption that higher K value kept internodes short as well!
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It's the +700nm that is known to cause stretch. High K cobs have slightly more output above 700 but all cobs are pretty low in the +700 range.

It's interesting to hear someone getting more stretch from high K though. I have someone conducting a test grow as we speak focused on CRI. It's too soon to draw any conclusions but all the samples are doing a good job at veg and daily measurements indicate stretch is similar across the board. There are a few interesting results popping up already, but due to the low plant count and it still being early in the game I don't want to get into details. I should have enough data in a couple weeks to ads something more to the conversation.
 
Rahz

Rahz

Well-Known Member
velvet_underground said:
Would it really be beneficial to mix cobs in such a small grow space?
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The spectrums will be averaged against one another at whatever ratio their being used in. I haven't played around with it but I want to as some point. It will involve digitizing each spectrum by relative value per nm, adding the values per nm and dividing each by the ratio sum.

=SUM((A2+A3+A4)/3) for instance and then converting the data back into a SPD chart.
 
Rahz

Rahz

Well-Known Member
velvet_underground said:
Would it really be beneficial to mix cobs in such a small grow space?

Rahz, I'm not in a rush and would love to see your results!
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A week long veg tracking has been completed. 5 lamps (3500/80, 3000/70, 2700/90, 3000/80, 3000/90) with 4 plants under each. Because of the small sample size I don't think the data is extremely useful, but it's worth looking at. The 2700K sample had a runt that only grew 1 inch over the week period so I took the average from the other three samples and used it for the 4th.

Method: The clones were given 4 days to acclimate and then measurements were taken over a week period.

At the end of the week the 2700/90 and 3000/90 had the tallest plants, though the overall growth during the week period tells a different story. On average the 3000/90 produced .5 inches more growth per plant than the other samples gaining a total of 15.5 inches between the 4 plants. The rest of the lamps gained 13-13.5 inches of vertical growth.

Observations: both 90CRI samples seem to have produced the most plant mass. Whether this was due to the clone selection or the light I can't be sure, but it could be posited that high CRI does produce more plant mass if we include the initial 4 days of acclimation and the fact that the best results were from the 90 CRI samples. I don't really have any strong thoughts because the sample size is so small.

The only sure conclusion is that any of the samples do a good job at veg. This isn't surprising because all the plants had adequate light levels with PPFDs over 700. Once stretch has stopped we will be jacking the PPFD to about 1300. :D
 
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