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Thread: T5 Bulb Brands?

  1. #33
    DaJimmer's Avatar
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    so yer saying that tubes will always be more light efficient because the light leaves the lamp better?
    sorry for the noob Question but describe lumens vs, Kelvin. lumens is the ammount of light given and kelvin is a quality of the light then correct? then you think I'm running a safe bet? they get about 14 hours right now and i understand what you mean about the crazy ammount of variables but am I missing anything is what im asking i guess

  2. #34
    Av8tor1's Avatar
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    Quote Originally Posted by DaJimmer View Post
    so yer saying that tubes will always be more light efficient because the light leaves the lamp better?
    If all other parameters are equal.... then yes.

    Quote Originally Posted by DaJimmer View Post
    ...sorry for the noob Question but describe lumens vs, Kelvin. lumens is the amount of light given and kelvin is a quality of the light then correct?
    Lumen is probably the single most abused term in describing plant lighting.

    Lumen is a measurement of the amount of energy that is emitted by a source, but is limited to the energy that is visible to the human eye. So I can have a very high lumen source that doesn't grow squat, or I can have a low lumen source that grows plants well.

    Seedjar is spot on about Kelvin, it is a reference to the temperature (in kelvin) that a black body would have to be heated to in order to produce the same color of light.

    Typically the higher the number, the more bluish the light source will appear. The lower, the more red.

    IIRC, During the normal daylight cycle, this varies form somewhere around 3000k to 6500k, with noon being about 5000k

    The most commonly used kelvin range for plant growth is 4100k to 6500K

    CRI is color rendering index, this is a measurement of how accurate the colors will appear. A rating of 100 is the highest possible. Typically the higher the number the more "broadband" the light source is.

    Quote Originally Posted by DaJimmer View Post
    ...i understand what you mean about the crazy amount of variables but am I missing anything is what I'm asking i guess
    This is subjective.... are your plants healthy?... are they producing good color/dew/etc?...are you happy with their growth and appearance?
    Can you have better, well of course... there is always room for improvement. But a lot depends on what is the limiting factor. The amount of light you can use depends on other variables... nutrient levels, CO2 levels, species etc etc etc.

    Be aware that there are not black/white answers to this stuff.... If you are not happy with your results, try another bulb. Give a 5000k or 4100k a try. You can also move bulbs closer if possible, energy levels vary based upon the inverse square law.

    One of the most overlooked but important variables is reflector design. Even with linear bulbs over half the bulb is pointed in the wrong direction. I'd rather have a T12 with a good reflector as a T5 with no reflector.

    and not all bulbs are created equal, while most will grow plants.... there can be a signicant difference between two bulbs having the same Kelvin temp.

    FWIW, the GE's are suppose the be some of the best of the CFL

    HTH's
    Av

  3. #35
    Let's positive thinking! seedjar's Avatar
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    Quote Originally Posted by DaJimmer View Post
    sorry for the noob Question but describe lumens vs, Kelvin. lumens is the ammount of light given and kelvin is a quality of the light then correct?
    That's close. Lumens measure the amount of certain colors being emitted by the lamp. But like Av said, it's just colors that the human eye sees. (A reptile heat lamp doesn't look very bright, and has a low lumen value, but they can emit enough infrared light to burn you and enough ultraviolet to give you skin cancer.) Lumens measure the intensity of energy put out by the lamp, but only a certain part of the energy.
    Color temperature (Kelvins) measure the average color of the light. The color of the light is related to the energy it contains, but not directly; it doesn't indicate the actual quantity of light. A light with a low color temperature has less energy than the same amount of light with a high temperature, but the colors themselves can't be used to determine how much light there is.
    As an example, think about standing on a road and watching the traffic that passes by. If you count the number of cars you see, you can get some sense of how much traffic flows on that road; this is like lumens. If you make a tally of the kinds of cars you see (commuter cars, public transit, work vehicles, freight trucks) you can tell what types of traffic the road is used for; this is like color temperature. Just knowing the percentage of traffic on the road that is trucks won't tell you anything about how many people use the road, and the number of cars on the road won't tell you what kinds of cars you should expect to see there.
    ~Joe
    o//~ Livin' like a bug ain't easy / My old clothes don't seem to fit me /
    I got little tiny bug feet / I don't really know what bugs eat /
    Don't want no one steppin' on me / Now I'm sympathizin' with fleas /
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  4. #36
    Av8tor1's Avatar
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    To muddy the waters even more, sometimes you want light for what it prevents from growing

    430-490nm wavelengths actually prevent the sporation of Botrytis while inducing the sporation of beneficial Trichoderma

    and this is only one example...

    This is why sunlight "kills" botrytis, and may be an issue for the indoor grower

    So if you have repeated issues with phytopathogens, lighting may be one of the variables you need to look at
    Av

  5. #37
    DaJimmer's Avatar
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    Hey thanks you guys. well met. with a few extra bucks ill experiment with some other bulbs n stuff just to research a little for myself. yea one thing i would like right now are dewier dros. i'll deffinatley experiment. thanks for the help

    ---------- Post added at 11:21 PM ---------- Previous post was at 11:18 PM ----------

    you ever heard of a kelvin rating like 10 000 to 20 000 "ultra day;light" used for anything?

  6. #38
    Let's positive thinking! seedjar's Avatar
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    Yes - those are typically used for lighting aquariums, particularly planted aquariums or reef tanks that have specific need for intense light. If I recall correctly, high-frequency light penetrates water better than lower frequencies. My understanding is that, for our purposes, bulbs of those colors are not necessary and possibly suboptimal.
    ~Joe
    o//~ Livin' like a bug ain't easy / My old clothes don't seem to fit me /
    I got little tiny bug feet / I don't really know what bugs eat /
    Don't want no one steppin' on me / Now I'm sympathizin' with fleas /
    Livin' like a bug ain't easy / Livin' like a bug ain't easy... o//~

  7. #39
    Stay chooned in for more! Clint's Avatar
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    I LOVE 10,000K. That's as high as you should go if you want to grow plants though. 20,000K is too high.

    10,000K doesn't work any better or anything, I just really like the crisp white light it makes. A couple of those and a couple of 6,500K lamps would be great. It's pretty

  8. #40
    Av8tor1's Avatar
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    Ron,

    Phillips Luxeon has white LED's with CRI ratings all the way up to 90CRI
    Now that is impressive!

    http://www.luxeonstar.com/

    I still say 5 yrs until they are a viable replacement, and when they do... they wont look like todays typical LED's, they will be more like Phillip's Luxeon light engines imho

    Av

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