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Fluorescent light question T12 vs T5

Discussion in 'Growing Areas' started by Marni, Nov 19, 2010.

  1. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I have been using 4ft 2 bulb fixtures over my flasks and am starting to try some T5 fixtures. The T12 are 40 watt and the T5 are 54 watt. I am a bit vague on all of this, but my understanding is that T5 put out more light per watt than T12. Does anyone have any experience with converting? Could I get by with only 1 bulb T5 replacing 2 bulb T12?
     
  2. Jon

    Jon Mmmm... bulbophyllum...

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    I don't see why not.

    Seedlings don't photosynthesize in flasks, so the only realy reason to have any light at all is for chlorophyll production. The plantlets get their sugars from the agar. So light intensity isn't as important in-vitro.
     
  3. This_guy_Bri

    This_guy_Bri weirdo

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    t8 and t5 are more efficient than t12
    t5 has more light output
    also, t12 ballasts and bulbs are to be phased out by the end of 2011, i think

    edit: sorry. didn't read far enough.... sorry this isn't too helpful
     
  4. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I appreciate the input. I have been buying fixtures from the hydroponic industry that accept T12 and T8. I had a lot of T12 that I had been given and was using them up. The first batch of T8 that I tried in them didn't seem to work, but it turned out to be that particular fixture. I have just purchased a couple of T5 fixtures to try since I am out of shelf space and lights again (already).

    I"ve been trying to find where I put my light meter, but it hasn't turned up. Thanks to Jon too.

    I take back what I said about the T8 not working in the fixtures, they only work for a few minutes and then stop. At least I can return most of them.
     
  5. Kyle

    Kyle Member

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    Where did you hear this? Not saying its not true, but to me that doesn't make any sense. If its green, it photosynthesizes. I'd be surprised if that wasn't an urban legend.

    Marni: I grow my flasks about 15 inches from 1 t5 light. Stuff does pretty good. But the fixtures so throw some heat. I had to line my shelfs with 1 inch of styrofoam insulation to prevent the flasks from baking from the bubls on the shelf below.

    Kyle
     
  6. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Thanks, Kyle. What is the width of your shelf? Mine are 2 ft wide. Are your shelves grate or a solid material? And how many hours a day are your lights on?
     
  7. Kyle

    Kyle Member

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    Heres a photo befroe I put on the foam:

    aimg.photobucket.com_albums_v322_KyleLucyk_IMG_4283.jpg

    The shelf is probably 18 inches wide and the lights are on for about 15 hours.

    Kyle
     
  8. Ray

    Ray Orchid Iconoclast Supporting Member

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    A T12 bulb typically puts out 40 lumens per watt. A T5 is more on the order of 90, so one T5 should be good for the same output as 2 T12's.

    Don't forget though, that 2 bulbs and their reflector may cover more of an area than a single T5.
     
  9. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Kyle, thanks for the info. And thanks for the image of your lab set up.
    Ray, that is really good to know. Even with the 2 fixture T12, I see some of the seedlings on the outside leaning to the light as they get up in size. I have been considering using two foot tubes going across the shelf and spaced at 1 ft and 3 ft (approximately). I bought one of the reflectors for a T5, but it seems very pricey for what it is. I have some heavy mylar that I am going to put under the shelves (above the lights) and on any sides where I don't need easy access.
     
  10. This_guy_Bri

    This_guy_Bri weirdo

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    i asked if t8 bulbs could work in a t12 fixtures or vice versa of a guy at a lighting store today and he told me no. i was hoping they would though. he's the one who told me they're phasing out t12
     
  11. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Thanks for asking them. I've been told the same thing at Home Depot, but the light fixture box clearly states that it can be used for T12 AND T8. It specifies the correct bulb ID to use for each of them. Clearly, it isn't working for me. I'm not sure that the company is going to take back all that I have purchased in the last year, but certainly most of them will go back. At least 12 fixtures will be returned.
     
  12. Ray

    Ray Orchid Iconoclast Supporting Member

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    The T8 was designed to be a retrofit for a T12 fixture, but being 32W for a 4-foot bulb, also requires a ballast retrofit. Driving a T8 with a T12 40W ballast will cause it to be brighter, but burn it out faster.

    Some typical numbers for a 4' setup:
    T12 40W 1600 lumens initial output (they all fade over time)
    T8 32W 2750
    T5 54W 4860

    By comparison, two 2' T5 @ 24 Watts each = 4320 lumens combined.

    T5's are the way to go, but I would think that a flat piece of mylar will not be as good of as reflector as would the specular aluminum ones that usually come with T5 plant lights.

    I did some testing with a Hydrofarm "High efficiency 2' system", as I have three over a jewel orchid terrarium (giving me about 1500 fc at a foot distance), testing the light intensity with- and without the included reflector. In this case zero inches from the light is actually about an inch from the bulb, right where the lip of the reflector ends:

    awww.firstrays.com_Pictures_reflector.jpg

    I imagine the mylar would be better than no reflector, but not by much at all, as it would reflect light from the upper half of the bulb out, not down - don't forget that the angle of incidence equals the angle of reflection - while reflectors made for them do.
     
  13. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Thanks again, Ray. Both the T12/T8 and the new T5's are from Hydrofarm. I'll play around with this a bit. I'll certainly add the reflectors if I can get away with less fixtures and less bulbs. I'm impressed, I doubt that my tests will get as far as graph form.:cool:
     
  14. Jon

    Jon Mmmm... bulbophyllum...

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    Troy. It makes sense, though. Why else would you use such a high sugar-content medium? I'd bet that if you put a replate in a kitchen cabinet, the plants would grow white.
     
  15. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    If you could grow flasks in the dark, tissue culture labs would be saving money by not having lights. Most everyone (who isn't selling lights) has told me don't bother with grow lights since I'm not trying to bloom them. But no one has told me not to bother with lights. I have been told that if I want to keep mothers from progressing I should put them in a darker spot. I have had some overgrown mothers in petri dishes stacked three high and the plantlets in the two lower ones are leaning horizontally to the sides where there is a bit of light.
     
  16. Jon

    Jon Mmmm... bulbophyllum...

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    Who said don't bother with lights? All I said is that light for in-vitro plants stimulate cholorphyll production. When you deflask plants (i.e. remove their sugar source), they're gonna need chlorophyll to produce sugars and survive. Perhaps they do photosyntesize in-vitro, but grow lights aren't necessary because of the available sugars. My earlier comment about photosynthesis is probably incorrect, but I stand by my statement about lighting inducing chlorophyll production.
     
  17. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I guess I misunderstood what you were saying.
     
  18. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I am part way through replacing my 4ft T12/T8 fixtures with new 4ft T5 fixtures with reflector. You were right Ray, the reflectors make a big difference. Also, the new fixtures are a much lower profile so I am going to be able to have less distance between the shelves and still be the same distance from the plants. I am not happy about having to reconfigure the shelves since I just did that over the last 6 months, but will be worth it in the end. I'll post pictures when get done, hopefully next week.
     
  19. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Here is a picture of the current lighting for my flasks. It is a pleasure to work in the room. I love the T5 fixtures. There is NO buzzing or humming, one 57 watt bulb easily replaces to 40 watt T12. I would highly recommend the extra expense if you are considering purchasing fixtures.
    t5.lights.flasking.jpg
     
  20. Jon

    Jon Mmmm... bulbophyllum...

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    Are you selling flasks? That's an incredible number of plants...

    Looks great, btw.