400 watt white mh??

Discussion in 'Lighting' started by foghornleghorn, Mar 24, 2012.

  1. I recently got two 400 watt white mh bulbs for free. I have a 400 watt hps for my grow box but it gets to hot in there and i don't have money to get better ventilation right now. I put one of the white mh in my light fixture and it works. it runs about 20 degrees lower. I understand that it has less lumens than a clear mh but do think it would be ok to use it to veg? i plan on getting better ventilation before i flower so i can use the hps.
  2. #2 YoSmokinMan, Mar 24, 2012
    Last edited by a moderator: Mar 24, 2012
    I'd steer away from that setup unless:

    -The MH is a conversion bulb.
    A regular MH can fire with an hps ballast but you're running the bulb out of spec, which could cause the arc tube to rupture.

    -The MH is a protected or open fixture rated bulb.
    Open fixture rated bulbs are designed to hold in any debris when the arc tube fails.
    Closed fixture bulbs can and will explode when they fail. Possibly starting a fire or causing injury.

    If you have an open fixture rated MH conversion bulb then go right ahead you can veg plants with that.
  3. I have a Sun System Light Fixture that is switchable. I dont know if it is an open or closed fixture. is there a way that you can tell just by looking at is? the bulb has nothing on it but i know it can out of a 400 watt light fixture.

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