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lighting Lighting question

PaulG

Extreme Member
My plants are at about 4 weeks since sprouting, and have been under 5000K flourescent tubes. I just looked at a box of flourescent tubes we had laying around and they are 6500K, same lumens. I read that 6500K is good; is it worth the time to swap out the lights at this point? Plants will have another 4-6 weeks on the grow table. Thanks in advance!
 
From what I gather 6500k is better for veg. 5000k is in the right spectrum, but I think if you have them laying around, it won't hurt, and should help a bit if you put them in.
 
yeah I would swap them out too, 6,500k has more light in the "correct" spectrum of available light that they can absorb.. probably won't really notice much of a difference, but it is better for the most part.. so why not
 
From what I gather 6500k is better for veg. 5000k is in the right spectrum, but I think if you have them laying around, it won't hurt, and should help a bit if you put them in.


yeah I would swap them out too, 6,500l has more light in the "correct" spectrum of available light that they can absorb.. probably won't really notice much of a difference, but it is better for the most part.. so why not

Okay, you both have confirmed my hunch. Since I have them, I'm going to swap them out. Thanks much!
 
Okay, it's a trick question, right? The Master of Experimentation would simply buy another fixture, start another batch of peppers and compare the results of the two bulbs. Then you would know for sure and help me decide if I need to keep my 5000K bulbs in the mix also, without me having to do anything!
 
well the problem is that you don't really want a full spectrum.. and since fluorescent lights have light in all the spectrum, they just "specialize" in one color or another, I would think it would be better to have more light in a spectrum that is useable to the plant rather than more broad band light, if he had.. if he had 5000k lights in there, and he had an extra 2,700k bulb or something I would say sure, go and use 1 of each, but 6,500k is just closer to the spectrum that the plant actually uses, so concentrating light in the area where the plant does not "use" as much, just doesn't seem necessary

but that is just what I have been taking away from a bunch of articles I have been reading on here and in science journals that I have been looking up since this topic has been coming up a lot on here.. and it gives me a way to avoid studying lol

here is a topic that was posted I think right after this one came up, pretty sure it was this morning.. but anyways, it had a good link to it. and it looks like PaulG has already found it lol.. and like he said on that page, the info in the article has some "iffy" points and are not really 100% worded correctly, but the main jist is good
http://www.thehotpepper.com/topic/28600-lumens-vs-par/
 
If you've got the time to swap them, then like the rest I'd say swap 'em :)


Done! Thanks Matty and Wrightdaddy!


Okay, it's a trick question, right? The Master of Experimentation would simply buy another fixture, start another batch of peppers and compare the results of the two bulbs. Then you would know for sure and help me decide if I need to keep my 5000K bulbs in the mix also, without me having to do anything!

Of course, silly me :doh: Maybe next year! Thanks for giving me more to think about, Ken!

There's nothing that says you can't have one of each in there to provide more of a full spectrum.

That's true, Y[sup]3[/sup]!


well the problem is that you don't really want a full spectrum.. and since fluorescent lights have light in all the spectrum, they just "specialize" in one color or another, I would think it would be better to have more light in a spectrum that is useable to the plant rather than more broad band light, if he had.. if he had 5000k lights in there, and he had an extra 2,700k bulb or something I would say sure, go and use 1 of each, but 6,500k is just closer to the spectrum that the plant actually uses, so concentrating light in the area where the plant does not "use" as much, just doesn't seem necessary

but that is just what I have been taking away from a bunch of articles I have been reading on here and in science journals that I have been looking up since this topic has been coming up a lot on here.. and it gives me a way to avoid studying lol

here is a topic that was posted I think right after this one came up, pretty sure it was this morning.. but anyways, it had a good link to it. and it looks like PaulG has already found it lol.. and like he said on that page, the info in the article has some "iffy" points and are not really 100% worded correctly, but the main jist is good
http://www.thehotpep...-lumens-vs-par/

I agree, Max - thanks for the detailed response! That is a good web summary.
 
Using the 6500k you would get plants that grow out rather then up, which is good, I agree 100% to use 6500k. However, 5500k is what the sun is at noon, 6500k is a overcast spectrum. It is closer to the blue light you see when it is cloudy out. Again the blue light causes structure growth resulting in less stretching and closer internode growth.
 
for standard fluorescents I run an equal combination of 6500K and 4100K...for CFLs, I run 6500K and 2700K in equal numbers
 
for standard fluorescents I run an equal combination of 6500K and 4100K...for CFLs, I run 6500K and 2700K in equal numbers

why the change when going from regular flouros. to CFLs? I can't remember but I know that regular tubes don't have "broken" spectrum as much.. or not really spectrum but since it is a tube, the light is more evenly distributed.. but I don't think that really has much to do with the spectrum so much.. but just curious as to the difference in changing the colors between types of light.
 
because the only 42 watt CFLs I can find locally are 6500K and 2700K
 
the 2700K would be better than the 4100K as far as I understand, but you'd want to use 6500K lights as well. The mid-range lights usually contain a lot of yellows which aren't readily absorbed in photosynthesis. The low-temp bulbs have a lot of reds (like the 2700K/2900K) but also a lot of yellows, and the high-temp bulbs have a lot of blues (like the 6500K). Reds and blues are most important for photosynthesis but ideally you should have both. Peppers do not prefer one or the other at any specific point during growth. If I had to choose between 2700K and 6500K though I would go 6500K every time.
 
^ yeah, that's why I was curious as to his choice with going with the 4,100k tubes.. unless he can't get 6,500k and 2,700k tubes there, which is kind of unlikely
 
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