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Thread: Lightbulb questions and 'experiment': wattage, spectrum, etc.

  1. #9

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    Nah, not dangerous... you should hear some of the install stories I hear

    I'm quite jealous of your regia btw

  2. #10
    turkeypig's Avatar
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    i'm sorry you had to see that. it's much smaller now that i've trimmed and transplanted it - it's probably set back a little.

    ooo! pretty spider.
    But really. Does it matter if the glass is open ya think? I hear that these things aren't waterproof, 'specially the bulbs.
    Forget about the mundane and meditate.

    Grow list:

    http://www.terraforums.com/forums/sh...d.php?t=124211

  3. #11
    mobile's Avatar
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    40cm is very close for a 400W fitting, so keep a close eye on the plants for any signs of burning. I would not removed the cover glass if I were you, having seen a MH bulbs 'explode'.
    Last edited by mobile; 07-29-2011 at 04:38 AM.

  4. #12

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    Quote Originally Posted by turkeypig View Post
    Does it matter if the glass is open ya think? I hear that these things aren't waterproof, 'specially the bulbs.
    Nah, the glass is there so water doesn't get to the bulb in unsealed fixtures, and to allow air cooling of the fixtures in sealed fixtures (the air generally being exhausted out of the room).

    I asked about the glass because if it was an open fixture you'd wanna "push" the air through the fixture, but if the glass is there it's better to "pull" even if the glass isn't "sealed."

  5. #13
    mobile's Avatar
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    Metal halide bulbs are high pressure. Some cover glasses are provided to act as an extra protection should the bulb fail. There are two common forms of metal halide bulbs, one which is a high pressure lamp within a low pressure envelope (looks like a bulb within a bulb) and the other type doesn't have the low pressure envelope.

    http://en.wikipedia.org/wiki/Metal-halide_lamp

  6. #14

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    mobile - not sure how it is in Scotland, but here in the U.S. all the horticultural fixtures and lamps are of the single envelope type when it comes to HID (disclaimer: I say "all" but there's probably an exception or two). The fixtures sold here in the states with cover glass are generally for air-cooling the fixtures, the protection of the lamp (bulb) being a byproduct.

    That being said... yes, I agree with you, you DON'T want to get water on a hot lamp. I've never seen it but I hear the results are unfortunate

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