how high to hang a 400 hps

Discussion in 'Growing Marijuana Indoors' started by TranSamage, Sep 26, 2007.

  1. i don't get it. my 400 is giving me small yeilds. I have good soil, ventilation, fertilizers, strains.... my plants are about 18 inches from the light. should I raise my light to 4 ft, then set my plants on the floor? Right now I have 4 rows of 2 plants and I want to pull a row every 2 weeks. uh 4-5 ft high?:confused:
  2. Sounds like they are a little too far for 400w. Get them as close as u can without burning ur tops. Place ur hand over the top of the plant with the back of ur hand facing the light. If ur hand is comfortable the nugs will be also.
  3. wuz curious of the same thing. however, my plants are only 2 weeks old. I'm using 400hps that is fixed to the ceiling at about 5 feet from the babes, but they are still small, I have some (5 18wglolux)glolux flos that I haven't managed to set up due to carpentry restraints( not too good with setting up light fixtures n shit) I used 2 18w flos for 1 plant to veg on my first grow. That worked great to veg then switched to the 400hps to bloom, got one gigantic main cola.
  4. what is the area of the grow room? I have my 400 about 18" from the tops, closer when the weather is cooler. Good ventilation/airflow will help allow the lamp closer. Check the heat by holding your hand next to the plants for a minute or so, and if the heat is building up on the back of your hand the light is too close. Best yield is when the lamp is as close as possible without overheating the plants. btw what sort of yield are you getting?
  5. I probably wouldnt expect too big of plants from one 400w light, expecialy with 8 plants. I normally just do the hand test and it seems to be good with 12 - 18 inches away from the top. I would use the hand test if I were you because 400w isnt realy alot of power and you might get a different result in heat. No matter what wattage though I would never keep the light further away than 2ft though.:wave:
  6. i have the same

    400hps/mh d.elect.bll

    and heat is an issue. I've run my light 1 hour to 1 1/2 hour then leave it off for 30 minutes. I don't know if that's healthy for the plants, but I assume take it as shade. Also it greatly reduces the heat for these little buggers. I have mine at ruffley 17" 18" and with a small 9" floor fan. My temperatures are between 79 and 89 and they're in seedling stage. autoflower strian and 3 others. they all seem to enjoy this method and are growing fine. Aslo my veg stages are going into flowering and they also seem to not mind the times. I use a timer for my light so that helps. hope this helps
  7. noobie doobie.. I'd be careful of that half hour off method you may produce hermies.. do you have another little flouro on while the 400 is off.. I would do that if you don't just so they don't get all messed up with the darkness for 30 mins every 2 hours...

    and transamage the closer the light the higher the lumens to the flowers and the fatter they are going to get.. unless of course it's 95 degrees in there.. I assume it's not cause you said you have good ventilation, so you want the light as close to the plants as you can get it.. I have my seedlings and moma's under the same 400 MH and I have it about 6 inches from the seedlings and 2 inches from the moma's seriously.. they love it.. the more light the better.. what you need to do is either veg long or get more plants up in that space you got.. you have to really fill up the canopy to maximize yeild.. open spaces where light is wasted = lesser harvest obviously.. but no as an answer to your question do not put the light 4-5 feet away you will get extremely stretched out plants and you won't be happy at all.. Keep it close.. and fill up that canopy!
  8. [quote name='irieluv']noobie doobie.. I'd be careful of that half hour off method you may produce hermies.. do you have another little flouro on while the 400 is off.. I would do that if you don't just so they don't get all messed up with the darkness for 30 mins every 2 hours...

    First, I don't want to seem like I'm stealing your thread.

    yeah, I got this little flouro, it aint much more than what you would put on a single plant. I can't really leave the mh on more than an hour 1/2 because the temperature hits up to 90-93. LW#2's male/f
  9. Well, originally I said that I had the light 18 inches above the plants and was getting a small yeild, which was 56 grams dried from a coma seeds, Amythist Bud, which is 80% Indica and they clam 15 - 20 % hmmmm so I guess I am just looking at the size, not the density. I mean If I don't totally break this stuff up, it turns into little solid embers that won't go away. The reason I want to move the light up is that I also have a kush that's like 80% sativa and it just wants to get tall no matter how close i put that fuckin light which means i have all these plants growing at different rates all on books that grow so fast they need to be lowered daily! well... when I had several thousand watts in the last place i never raised and lowered shit... i mean 40 girls in a room to deal with is fun but..... so i figure that i can utilize a 4 foot square area so i raised it that high and yes, they are streatching, but the buds are WAY BIGGER. Before, when the light was 18 inches away the buds were the diameter of my thumb... WET!!! Now they are as big around as my wrist at 5 weeks!!! weird, huh? And, heat is no issue at all. remote ballasts rule. I can touch the hood also with no burn whatsoever. The only heat comes from the bulb, so I hung a fan which blows right accross the under side of the bulb and just leave the clost door open, but I can totally close it and it gets to about 85 degrees in about 2 hours. Not bad if some one comes by. So thanks everyone oh yeah
    NEWBIE DOOBIE..... Dude yer gonna get hermies dude... seriously.. stop that!!:devious:
  10. Hey, a 400w can be kept almost as close as 8 inches away from the tops of the plants. So long as you have an exhaust system you'll be fine. Also, a fan blowing between lights and plants is also a good idea.

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