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mh/hps

smileyguy697

smileyguy697

I just bought a 400 watt ballast, hood and mh/hps bulbs. How high should they be from my seedlings? I'm afraid to put it to high cause i don't want leggy plants but the higher it is the more i can pack under it. I'm going to start dwc here in a few days and was also wondering off its high enough so the dwc plants don't burn up will my seedlings still get enough light on the floor. I'm thinking they will be ok since they were under t8s before and this is way brighter but I'm sure i can get a good answer from someone who's used them before. Oh and will i need to harden them to this light from the t8s
 
I'd suggest starting off at 24" above and take a temp reading.
Then move closer little by little always checking temp.
Using a fan too will allow you to keep it closer without cooking your plants.
You may want to consider using some type of reflective material for your dwc set-ups to keep reservoir temps down.
Good luck with your grow.
 
Great advice from CR above. Those bulbs put out some heat and if the room you're in is small you may have to do some venting.

Good luck.
 
Yeah it is small. I live in an apt and didn't know how hot it is gonna get. Can't really cut holes in windows or walls for exhaust. Lol... Any other ideas?

Actually the rooms not super small. Its a second bedroom but not sure of the dimensions
 
The way i do it, i move my hood than put my hand over the plant, if my hand keeps getting warmer, i know its to close and i move it up until my hand does not get hot anymore,
 
I used to be very afraid of burning my young plants in a closet space under 400w MH, too. If you have a fan running and you're still concerned, start it off at 3 feet, and lower it a few inches daily until you feel good with it. If they're getting 18+ hrs of light daily (young plants should, IMO), they won't get too leggy at 3 feet, you're just not getting all the lumens you paid for. The beginning of my current Glog is a good example of what is way too high, because I didn't have enough chain. Now, it's still a little too high just because it has to provide for 16 plants, but about as low as I can go.
 
Try not to over think it.

2' above the plant is fine. If you haven't started the DWC yet, put it under the light from the very beginning so it is used to it. At 6" you can burn leaves, but at 2' you should be fine. IMHO, I don't think that they put off that much heat at all. Enough to warm up a small room a degree or two, but that is about it. you want the plants to be a little warmer than room temp anyway. If you have it in a bedroom, I wouldn't worry about vents, in a closet, I would think about it.
 
I fired it up last night and below the lights where the plants were it was reading 82 degrees. I need to come up with something better to hang it from before i start using them. Also wich one burns hotter? I've been lurking around and its looking like its the mh but haven't seen anyone say from experience. I also saw a few people say they just use one bulb the whole grow?
 
smileyguy697 said:
I also saw a few people say they just use one bulb the whole grow?
Click to expand...

http://thehotpepper.com/topic/37871-mh-to-hps/

I also have a 400w ballast that supports both MH and HPS, and like many other growers, I learned that there's really no need to change. It's a common misconception fueled by the popularity of Cannabis cultivation that plants need red light to produce flowers, which is simply not the case with peppers. They're also not photoperiodic, so they'll flower and set fruit just fine with over 12 hours of light daily. I've produced peppers under MH anywhere between 14 and 18 hours of light.
 
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