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Growing with metal halide lights

Discussion in 'Newbie Central' started by greenjimmy, Oct 8, 2006.


    greenjimmy Active Member

    I have a 1000 watt metal halide set up. After my seeds sprout they grow very slowly for the first few days and gradually turn yellow and die. this has happened three times now. Its in a closet space that is not easy to keep cool. some people have said I might need some kind of light filter. some people have said my lights might be too close. I really don't know what I am doing wrong. the lady I bought the light kit from said the bulb was a "metal halide bulb, but that it has the full spectrum of light from metal halide and high presure sodium combine, so I can use it from start to finish". I'm learning as I go, was it a mistake to get that bulb. Should I have just got the regular metal halide. Is my growing area to hot. I really need some Ideas here, I spent alot of money on these lights.

    Sublime757 Well-Known Member

    what are your temps running at bro? and are you pH'ing your water? also, try starting off your seedlings with fluorescents until theyre about 6" tall. then keep the metal halide light about 20-24 inches away from the top of them. and do you know what the bulb was called she sold you? because ive seen two parts bulbs that incorporate a 400w MH and a 600w HPS all in one bulb. but i have only seen these once.

    greenjimmy Active Member

    I don't know what the temps are at. But they r really hot. what would be an ideal temp, and what would be the best way to cool. no i'm not ph'ing my water and I don't know how. The lady I bought the kit from only said it was a mh bulb but that it also had the same light spectrum of hps, she didn't say any other kinds of names. The name on the box said something like argosun or ergosun, but I threw it away. Is there any books you could suggest. I really have know idea what I'm doing. Also, would any kind of flourecents work or is there some kind of special ones specificaly for growing

    crickitmd Well-Known Member

    if its in a real small grow space, and you cant exhaust why dont you use a smaller 400 watter?

    Sublime757 Well-Known Member


    Sublime757 Well-Known Member

    a 400w bulb would have been cheaper and easy to maintain temps in a grow room as well

    Sublime757 Well-Known Member

    you can use compact fluorescents for them or just use the cool white and warm white bulbs in combination for seedlings

    OmegaVermelho Well-Known Member

    Temp is more then likely ur prob, but just out of curiosity what type of medium are u using...i remeber that in my 1st attempt i mixed to much nutes in the soil and the Nitrogen was taking the soil ph as low as 5.2 wich was burning the plants down....

    mogie Well-Known Member

    Sounds like you are cooking those poor little things. You should have a termometer in there. Never let it get past 85 degrees.

    A flourscent will work for seedlings. But once they start to put on growth the flourscent will just make them leggy and worthless.

    You will need at least a 400 watt and better a 1000 watt light. Not halide! High pressure sodium is the way to go.

    You will need two bulbs. One for growth and one for flowering.

    You first need the right set up. This included venting. This will prevent over-heating so you don't cook your plants. Also a good timer (not a cheapie from WalMart).

    I set my grow room up in our spare bath. We use the bathtub to set the plants in (no water problems). The window above the tub is walled off. In one half is an air conditioner for summer growing indoors. The other half allows the hot air to vent outside via the exhaust fan. I have my light on wheels attached to the ceiling so I can raise and lower it as I see fit.

    I keep a termometer in there so I can moniter the temp. and I also keep a plant moisture meter in there so I know when to water. Overwatering is a newbies biggest mistake. I don't have a problem with humidity since the exhause fan runs when the light does (18 hours a day).

    Every set up is a little different as very grow room is a little different. But the correct set up is vital. I can grow killer smoke when I respect the plant and let it grow under it's best conditions. Well killer seeds help too!

    ViRedd New Member

    If in soil, a PH of 7.0 is fine.


    skunkushybrid New Member

    OPEN THE DOOR TO YOUR GROW SPACE NOW! You'll have to leave it open until you can buy an exhaust system. If you can't afford one you're going to have to leave the door open, period. Can you take pic's? Also if you have the cash buy some Co2 from the shop, if not there are some excellent posts on this site on how to make your own. Co2 enriched air enables the plants to handle much higher temp's. I read in Soft Secrets that they can take temps up to the mid 90's if the Co2 concentration is right. Soft Secrets is a newspaper for growers printed in Holland.


    What is the difference between a coated mh and non coated mh

    Pot3r Member

    yea would like to know that too, also is it better to buy a bulb from my grow store, or is the one at lows the same thing, just diff brand? i mean i know that ima want to conversion bulb down the road, but right now i want to know what the besst 400w mh bulb is for me to get? think the one at lows is 23$, one t my grow store is 31$, but donno wich one to get, im guessing the one from the grow store is going to be for growing? so better spectrum? or is the one from the lows simuliar enof that its worth the 10$ saved

    Bic Member

    Anyone? Know what powder coating does?
    Bonzi Lighthouse

    Bonzi Lighthouse Well-Known Member

    I can almost guarantee you are cooking your plants. You have to vent your grow room. Best way to do this is an air cooled hood. Sun Systems has a nice selection. Here is one that is Ideal for a closet grow, note the vent fittings are on the sides not the ends, comes in both 4" and 6". INCLUDES GLASS, SOCKET/CORD, AIR-COOL FITTINGS. If you do not have a Sun Systems Ballast you will have to hard wire your existing ballast power cord.

    Oh and here is a nice picture of a seedling fried under a 400w Mh light.

    and a picture of a grow room setup to kill seedlings.

    Attached Files:

    Bonzi Lighthouse

    Bonzi Lighthouse Well-Known Member

    Powder Coating is how some metals are painted
    XS Brain

    XS Brain Active Member

    It's the typical grey or white coating that allows metal to not rust. :)
    not relevant to anything important in growing I'd say. It more about longevity of parts.

    EveryDayToker. Member

    Try using top quality soil With water form any river around or distilled bought water form the store. Most likely your plants are turning yellow is the water. You can pick up a cheap Ph/Light/Moister deal form Low's its about 10~18$ This is what it looks like but I can never find it on the lows web-sight.
    http://www.alibaba.com/product-gs/347277419/3_IN_1_moisture_LIGHT_ph.html?s=p. My soil stays around 7.8 Its high but for some reason its working great. (Underground Well-Water)

    As for the lights try to get a oscillating fan or box fan. For veg Temp should be around 76 ~ 80 For flowering I've seen better results and more potent 72 ~ 70. You might want to pick up a t-8 cool-white fluorescent to get them started cost around 20 ~ 30 for a duel side by side 3 foot form home depot. fluorescent could run all day but that 1k watt metal I would only run 16 hours on 8 hours off for first 2 months or so. I've seen better results with just LED 15w high intensity grow blub And much cheaper to run.

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