User Tag List

Informational! Informational!:  0
Likes Likes:  0
Results 1 to 6 of 6

Thread: Looking to update my bulbs! Need some knowledge

  1. #1
    Is ready to take this hobby to a whole new level DavyJones's Avatar
    Join Date
    Dec 2007
    Location
    Cleveland, Ohio
    Posts
    958
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Looking to update my bulbs! Need some knowledge

    As the subject reads. I currently have 2 grow racks with 2 20W fixtures each. I'm currently just using 2 GE T12 20W cool white tubes from wally world. I started researching when I heard cool white alone doesn't provide enough spectrum for good growth. I also wanted a bump up in lumens. When I started looking at some broad spectrum bulbs, I noticed their output was considerably less. (1180 with the GE, about 900 with grow bulbs.) What are some good choices? Can I upgrade to HO bulbs by just upgrading the ballast? This is for mostly neps and drosera. Any feedback is appreciated.

    ---------- Post added at 12:07 PM ---------- Previous post was at 11:55 AM ----------

    I was also considering a sheet of mylar behind each stand to reflect some light back and not lose so much to the surroundings.
    "We are in a sense the Universe trying to understand itself. By Observing it we are observing what we are." - Phillip Plait

    Growlist: Updated 1/11/12 http://www.terraforums.com/forums/sh...d.php?t=110846

  2. #2
    Av8tor1's Avatar
    Join Date
    Jan 2007
    Posts
    4,811
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    Davey

    Lumen is a measurement of light intensity as it appears to the human eye. Being such, it is heavily biased toward the green and yellow part of the visible spectrum. These same wavelengths are the regions least used by plants for photosynthesis. So in a way, Lumens are a measurement of the light energy that plants don't use LOL. This is why many "Gro-Lux" type bulbs have very low Lumen ratings. A much better metric is PAR and PUR. However, this is almost never a known value.

    The best bulbs I ever used were an extremely low lumen but high PAR/PUR and PAR/watt. But unfortunately they are not available in anything other than T12.

    Before you start changing anything, how efficient is the fixture itself?.... Approximately 2/3rds of the linear fluorescent bulb* is pointed in the wrong direction. Properly designed reflectors redirect this energy into the right direction. So a properly designed fixture can provide 300% of the light energy compared to the same bulb with a poorly designed fixture.

    There are already endless pages of threads/discussion/details/etc of the values of wavelength. Most bulbs will grow plants... but some bulbs certainly can do it better.

    So, while you may do better with a different bulb.... first look at your reflectors, improving this area may provide a considerable gain in usuable energy at little to no additional operational cost.

    That being said, most bulbs of 5000k with a CRI of 85 or so provide the highest PAR values. Natural sunlight varies from 4100k-ish to 6500k-ish with 5000k being noon

    (* This is why CFL are not as efficent as linear tubes in a watt vs. watt comparision.... So much energy is lost due to physical design considerations)
    Last edited by Av8tor1; 06-16-2011 at 10:34 AM.

  3. #3
    does this rag smell like chloroform to you? boxofrain's Avatar
    Join Date
    Dec 2010
    Location
    Brookings, Or. USA
    Posts
    523
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Gawd I love your post's Av8tor1!
    "the memories of a man in his old age, are the deeds of a man in his prime"

  4. #4
    Av8tor1's Avatar
    Join Date
    Jan 2007
    Posts
    4,811
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    thanks .... I think LOL

  5. #5
    Is ready to take this hobby to a whole new level DavyJones's Avatar
    Join Date
    Dec 2007
    Location
    Cleveland, Ohio
    Posts
    958
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    So what would one look for in a better reflector? Is it something as simple as putting some sort of reflective film or coating inside the reflector?

    Awesome information about the Lumens BTW.

    Does that mean that a good plant bulb won't appear as bright to my eye, but will have a better impact on the plant?
    "We are in a sense the Universe trying to understand itself. By Observing it we are observing what we are." - Phillip Plait

    Growlist: Updated 1/11/12 http://www.terraforums.com/forums/sh...d.php?t=110846

  6. #6
    Av8tor1's Avatar
    Join Date
    Jan 2007
    Posts
    4,811
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by DavyJones View Post
    So what would one look for in a better reflector? Is it something as simple as putting some sort of reflective film or coating inside the reflector?

    The best T5 reflectors are 95% efficient faceted mirrored aluminum.. If you have typical shoplights you can help them quite a bit by lining them with mylar.


    If they have no reflectors.... it is probably best to put those to use iin the garage or basement and get you something else for the plants.


    Awesome information about the Lumens BTW.

    Does that mean that a good plant bulb won't appear as bright to my eye, but will have a better impact on the plant?

    Well, yes and no.... if it was only a case of the photosynthesis curve then yes that would be true.... but there are other needs. The best combinations are usually a gro-lux type bulb mixed with a broad spectrum bulb.

    http://bluegrasscarnivores.com/research1/grolux.pdf

    But dont get too lost in the fog of bulb selectcion... first make sure you're using what you already have to the best you can. I'd rather have a 3-5 dollar bulb with a good reflector than a 10-20 dollar bulb with no reflector.
    Last edited by Av8tor1; 06-16-2011 at 05:34 AM.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •