FYI: Light Measurements under T5 lamps

[kavanaru]

I mean, temps outside typically goes down to -10°C and in some werid cases to -15°C, however this is quite rare (normally we have very mild winters here, around 0°C) with my balcony is a different story It faces south-east and i can completely close it (glass panels), which makes sort of a cool houes for my kids, and also isolates the rest of the appartment very well... the "wall" that faces the balcony is also out ofglass, so i get enought sunlight in the appartment all the time and because ofthis I have never used the heating system (I like my room also a bit cooler)

[LinhT]

Ramon,

I have a question regarding the 3000k/6500k ratio thing. How does one know what ratio to use and have you found a big difference in using all 6500k without any 3000k at all??

[kavanaru]

Tracy, if you use only 6500K lamps, the light is very blue, and if you use only 3000K it is too red (both cases are actualy vey disturbing when see your plants )

I know I have read somewhere (cannot recall it right now) that for a healthy grow of the plants you should use a ratio of 3:1 or 4:1 (6500:3000K), which should make a good average similar to the natural daylight spectrum... I use 3:1 because of the set-up of my lamps (6 and 4 tubes) and because it gives a very "natural" look

You can see in the pictures (Lc. Su Nan Hwi 'J.D.') , the optical effect of using only 6500K (blue flower) & only 3000K (red flower). The intermediate picture looks very very close to the real color of this plant and teh way it looks like under a 3:1 ration. Note: The picture was taken under only 6500K with light calibration in the camera (Thanks Ross for the help!), as it has been shown to be the most difficult flower I have to be photographed: no matter what I tried (daylight, flash, T5, or combinations), the flower always looked too red in the pictures

[Ross]

Tracy, I have been guilty of spreading the info that a mix of color temperatures is great - just for reason Ramon describes: it makes color rendition of the blossoms look correct. Here's what I do:

The color temperature of the sun at noon at the equator on a clear sky day is approx 5500K. Under early morning skys in open shade it can be as high as 8000K or higher. If I were trying to capture a truly blue flower, I would use the higher K times of day or open shade, etc. 3000K is close to sunset or the way the sun would appear late in season. Supposedly plants react to low K by forming spikes. Or that's what I've heard.

To get the average Kelvin color temperature of your bulbs, add all the bulb color temperatures together and divide by the number of bulbs. For instance I am using 6 tubes @ 6500K and 2 tubes @ 3000K in my 8 tube fixture. That would average to 5625K or slightly bluer than mid day sun - close enough.

Keep in mind the plants don't care. We don't do this for their benefit entirely. It makes our viewing experience that much better and picture taking easier, as Ramon describes very well above. Nice exmples, Ramon. Best I've seen. Mayby we could get a mod to split this discussion off and move to photo forum?

[LinhT]

Thanks, Ramon and Ross, for the explanations . I have several of those New Wave fixtures and definitely think the color of the plants looks much better under my 5000k T5's compared to the 6500k or 3000k alone.

However, I guess what I was trying to ask is have any of you actually tried growing your plants under 6500k alone for an extended period of time and noticed a difference in growth with regards to blooming, compared to using the mix of 6500k + 3000k?

I've read that red light (3000k) is for "blooming" while blue light (6500k) is for "vegetative growth". I'm wondering if any of you have actually found this to be true though? Did your plants really GROW and BLOOM better under the combo of 6500k +3000k (3:1)? Or were your results the same under all 6500k?

I ask this because I know an elderly man who use to be a professional Catt grower. He now grows over 400 orchids in his basement under 4 or 5 HPS fixtures. HPS is more "red" while MH is more "blue". He doesn't use any MH at all but his plants grow and bloom well. So I'm a little confused....

Not sure if I'm making any sense, I'm not explaining this very well.

[Ross]

Originally Posted by LinhT

Thanks, Ramon and Ross, for the explanations . I have several of those New Wave fixtures and definitely think the color of the plants looks much better under my 5000k T5's compared to the 6500k or 3000k alone.

However, I guess what I was trying to ask is have any of you actually tried growing your plants under 6500k alone for an extended period of time and noticed a difference in growth with regards to blooming, compared to using the mix of 6500k + 3000k?

I've read that red light (3000k) is for "blooming" while blue light (6500k) is for "vegetative growth". I'm wondering if any of you have actually found this to be true though? Did your plants really GROW and BLOOM better under the combo of 6500k +3000k (3:1)? Or were your results the same under all 6500k?

I ask this because I know an elderly man who use to be a professional Catt grower. He now grows over 400 orchids in his basement under 4 or 5 HPS fixtures. HPS is more "red" while MH is more "blue". He doesn't use any MH at all but his plants grow and bloom well. So I'm a little confused....

Not sure if I'm making any sense, I'm not explaining this very well.

You explained yourself very clearly. I think the reason the other person does so well is that plants aren't nearly that finicky that the percent of 6500 or 3000 makes much difference. Lots of folks here on the board use plain old shop lights and do very well. I choose to use a mix purely for my own benefit, not the plants. There are purist coral reef tank hobbyists that use LED lights in pure blue and pure red. Now that's a different matter entirely. But our lights mostly have most of the color spectrum. No I have not tried what you ask, but I see no benefit of changing what you are now doing. I really doubt there would be any discernable difference. Just my 2 cents.