MH and HPS combined lighting?

Discussion in 'Advanced Growing Techniques' started by greeneacres, Aug 16, 2008.

  1. ps the grow area is 3x3
  2. i think you would have major cooling issues with a system that large.. Whats wrong with dual 150w hps or 400w hps? But then again i guess it all depends on your grow style.. Hydro or soil? How much upwards space do we have to work with? How many plants...?

  3. lets say the grow area was pumped with some cool air from an ac answer your questions first my concern with using 150w of hps is not enough for the best yield even if it was accompanied by a 150w metal halide. second i would say using a 400w hps would be great but would 200w hps and 200w mh be better? or would using only 200w of hps even if it had the help of a 200w mh give a worse result than 400w of straight hps? phew

    to answer your other questions hydro, 7ft, 9 plants (3x3) in 5 gallon buckets each a square foot in diameter.
  4. You're going to get about the same type of yield with 150W as you will with 250W as they're both low power.

    I think you're taking things a little too simply here. You state 250W + 250W = 500W but what you're not taking into consideration is that the lower the bulb power, the less penetration power you have.

    In other words... putting 2 x 250W at the same distance above the plants as a 500W HPS would be ridiculous as the light from the 250W's won't reach the same distance... they're lower power light sources and would have to be much closer to the plants to be effective.
    Here's a simple light FAQ for reference

    Using this guide as a reference you're going to see that a 250W bulb actually only covers about a 2 square foot area.

    My recommendation would be to build your light reflector to hold 2 250W bulbs and make one HPS and the other MH... just like you wanted. By doing that you'll be a bit over wattaged for a 3X3 area but you shouldn't have to resort to CO2 or anything exotic.
    Running both lights will indeed maximize the potency of your grow as the HPS grows the densest flowers but the UV B from the MH is needed to create the most THC.

    I also recommend using LST or Scrog ANY time you're using lower power lighting. Both techniques allow you to keep most of the plant close enough to the lights to be effective.

    Personally I would use a 400W switchable ballast for that area and use LST (to keep things simple)

    For maximum yield and potency I would try this lighting schedule

    Use the MH for the vegetative period.
    Use the MH for the first 2 weeks of 12/12
    Switch to the HPS until the trichomes begin to form heads
    Switch the MH and the HPS every 2 days until the end of the harvest.

    From what I've read, (and this could be total BS) the round head on the end of the trichome actually focuses the UVB light on the resin inside the stalk, triggering the plant to create THC. (The plant forms the THC as a protective measure against damage from the UVB)

    So... MH to get the densest vegetation and branching
    HPS to pack on the densest flower formations
    and then MH to increase potency while switching with the HPS to maintain flower density.

    Anyway.. sounds like a lot of work so I'm going to give it a run and see what difference it really makes. :)
    If it's a lot of work for nothing... I'll most likely go with mostly all MH grow as it's really the potency and complete medical workup that I'm looking for. Flavor of the month has no attraction for me.

    GROW ON! :)
  5. #6 lionovjudah, Aug 16, 2008
    Last edited by a moderator: Aug 16, 2008
    combinatation lighting is great as it gives plants a more fuller spectrum of blues/whites/yellow/red, as for the power of the unit well thats speaks for its self i have known guys who use low wattage units to save on electric some of the more experienced grower's get good yeilds but if you dont want to leave things to chance then step it up a notch in the power department more light means more thc, stronger pot and denser buds which we all want, oh yeah 1 more thing you might be intrested in, HIGHER YEILDING PLANTS im a big fan of hps & m/h 400w and 600w all the way for coffe shop grade buds, have a go and u wont look back (one love da lion ov judah) best of look bud (ya guy hydroranic knows his shit have a word with him)
  6. thanks for all the help but im still not clear on where i should start...for example...whats better 600w total of hps or 600w total of hps(300w) and mh(300w) in the same hood. in other words should i split 600 watts between the two bulbs (hps and mh) or should i just go with 600w straight hps.

    ps this is just an example. you could use whatever numbers you like.

    second, does anyone know if 300 watts of hps lamp would cover a 2x4=8 square foot growing area?

    third, bubble bucket users. i hear the plants get very wide due to the amount of root space. is there enough room for two bubble buckets in a 4x2 grow area

    grow journal anyone?

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