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 Post subject: Testing T8 LEDs for growing flasks
PostPosted: Wed Dec 09, 2015 10:49 am 
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Joined: Tue Jun 01, 2004 11:43 pm
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Location: Canyon Country, Ca
I thought I would start a thread on a test that I'm running in the lab. I really want to switch from florescent bulbs to LEDs. I run 5 to 6 shelves with 4 foot florescents all the time, so switching to LED could be a significant savings on electricity and would reduce the heat generated in the lab. But of course there are no horticultural grade T8 LEDs yet. So I had been doing research to see if I could find any that had the right color profile specifically for growing orchids in flasks.

I ended up ordering three different bulbs from Aspect LED (http://www.aspectled.com). These are their descriptions of the 3 bulbs. They have more information with spectral charts on their website.

Warm White "Warm White is most popular light color for residential applications and has a bit of a gentle/soft warmth/yellowish hue to it. Warm white is the same color as a standard incandescent light bulb, which is 2700K."

Cool White "Cool white is popular for commercial (office/hospital/medical/munificpal) applications. It is also very popular in modern-style residential projects. Cool white is a very pure white, it doesn't really have any yellowish or blueish hue. Cool white is the same color as most fluorescent light bulbs, which is 4000K."

Day White "DayWhite TM is the brightest LED light color that we offer and is popular in industrial and other applications where a high color temperature and high brightness is desired. DayWhite is an ultra-pure white, with a bit of a blue-ish hue, designed to mimic the color of natural sunlight. It is the same color as metal halide bulbs, which is 6000K."

I ended up starting my testing using one Cool White and one Day White bulb. I also ended up getting a nice work bench in the process that housing my LED fixture under the bottom shelf. :-)

Attachment:
IMG_1287_640.jpg


I'm only 2 weeks into this test, but so far the results are actually really good. The output of these lights is a bit brighter than a florescent bulb, so you do have to be careful. But so far I'm noticing really good leaf color and growth.

I will eventually test out the Warm White, but I suspect for vegetative growth there is going to be little benefit.

Once I see I'm getting good results for an extended period of time (4+ weeks), I'll set up one of my main shelves with the Cool White and Day White. Then I can try the Warm White on my testing shelf to see if it's better or worse.

:-) Rob


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 Post subject: Re: Testing T8 LEDs for growing flasks
PostPosted: Wed Dec 09, 2015 11:16 am 
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Joined: Tue Jun 01, 2004 11:43 pm
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Location: Canyon Country, Ca
BTW... One note about these bulbs... They are direct wire to AC, so you remove the ballast from the fixture and directly wire into the T8 mounting brackets.

You get two levels of efficiency with this approach, the actual LED bulbs use about half the electricity of the florescent bulbs. Running a ballast also uses some electricity, depending on what it's efficiency was will determine the savings. But the net savings is usually more than just what you get from the difference between the bulbs.


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 Post subject: Re: Testing T8 LEDs for growing flasks
PostPosted: Wed Dec 09, 2015 12:44 pm 
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Thank you Rob for sharing your test. This is something that I will look into soon. I have three shelves of old T8 that I like to replace with LED in my grow room.

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 Post subject: Re: Testing T8 LEDs for growing flasks
PostPosted: Thu Dec 10, 2015 7:58 am 
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Location: Oak Island, NC
Naoki Takebiashi (please forgive a potential misspelling) is a professor at U of AK, Anchorage, and has been doing a lot of scientific analysis and testing of LEDs for orchids.

He has found, in general, that "warm white" tends to give more PPF "bang for the buck", but that, of course, will depend upon the phosphor used to create the "white" light.

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Ray Barkalow, Orchid Iconoclast
Using science & logic to improve orchid growing


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 Post subject: Re: Testing T8 LEDs for growing flasks
PostPosted: Thu Dec 10, 2015 12:22 pm 
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Joined: Tue Jun 01, 2004 11:43 pm
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Location: Canyon Country, Ca
Do you know if his focus was on vegetative growth on seedlings or more focused on broader growing with adult plants to also encourage blooming?

Best, Rob


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 Post subject: Re: Testing T8 LEDs for growing flasks
PostPosted: Fri Dec 11, 2015 6:23 am 
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I don't think he was focusing on any particular stage of growth, but was looking at the light output itself, particularly in terms of efficiency - photon flux per watt.

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Ray Barkalow, Orchid Iconoclast
Using science & logic to improve orchid growing


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 Post subject: Re: Testing T8 LEDs for growing flasks
PostPosted: Sat Feb 18, 2017 8:37 pm 
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Joined: Sun Oct 18, 2015 7:47 pm
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Location: Berkeley, CA, USA
Hello Rob...did you come to any conclusion as to which worked better?
Thank
-Ross


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