150w HPS Questions

About how far from the canopy should my light sit? temps are about 84 deg f, i know thats on the hi-side but should be ok. in a cab about 30" high, 24" wide, and 14" deep. still undecided on a basic lst or scrog..

With only 30" to play with I would keep the light as high as possible, and don't grow sativas. Peace

yeah i have it about as high as possible, its about 13" from tops. Considering different profile pots if this is too close and am going to lst or scrog to lower overall height. mind you its a personal grow and somethings better than nothing.

Lst for sure. Get the temps down or yield and quality will suffer. Buds will be airy if its too hot also.

agree, LST them down, and do sumthing about them temps, try to get em down under 80F a ventilate/fan a open window with a pice of ducting what ever, run the light at night and let em have there dark time doing mid day etc. tho IMO a cool tube is the only way to go with a HID light and a small box, not only for temperatures but also so you can keep the light close and provide some good strong light for your Bud`s


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150 watt hps is gonna be optimum from 4" to 12" from the plant. Here's a chart to refer to : http://www.thctalk.com/gallery/data/500/HPS-Light-Distance-Chart.jpg

Lol yea he beat me to it : )

Slipon said:

agree, LST them down, and do sumthing about them temps, try to get em down under 80F a ventilate/fan a open window with a pice of ducting what ever, run the light at night and let em have there dark time doing mid day etc. tho IMO a cool tube is the only way to go with a HID light and a small box, not only for temperatures but also so you can keep the light close and provide some good strong light for your Bud`s


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thanks for the tips. yeah its easier for me to have the lights on at night anyway, ill come up with something for the heat. happy to read that i can get the canopy 4" from the lights, thought i was going to have to keep them farther away.

You won't be able to get as close as 4" with an open 150HPS, unless you have a fan blowing on the tops of the plants keeping them nice and cool. You can test it by placing your hand at the same distance from the light that your plants will be at, you'll notice that unless you have a fan cooling your hand, it will get pretty warm there. Plus, your plants will be under those conditions for 18 hours per day, so you want to make sure they're comfortable.

yeah i should probly mention that the cabinet im using is not closed. the side that faces me 24" wide x 30" high, is open. i have a 10" fan blowing at the light from outside the cab on the floor for cool air/circulation to the right and the majority of it is covered with a windshield reflector that stands in front that i can adjust however. i can keep my hand a few inches away and it doesnt seem uncomfortable. Whats an ideal humidity?

yea the 4" will require a cool tube or similar



can actually make a nice DIY from small HPS light out of a glass tube from a regular oil lamp, a small budget axis 4" ventilation and a pice of aluminum ducting and your off, able to keep the light at them 4" Im sure and with temps under 80F

when I started out with my 600W HPS it made my room jump from 22C to +34C !! got my self a 6" ventilation (380 CMF) and got it down on around 30C
had to run it at night (like you, it also suite me better as Im at home) before I could get under them 30C, more or less 28-30C doing the night

fist when I got a cool hood with my 6" ventilation on it I could maintain them perfect 24-26C

with out a cool tube I would try to keep a 150W at 8" to get them +10 Lumens, see if running it at night and use a fan pointed up at the HPS can get you acceptable Temps

humidity will be best at 50-60% in Veg and 40-50% in flowering

tho as long as you can keep em around 40-60% all grow you will be fine, I would fist begin to worry/act if I had a RH under 30% in Veg or over 60% in flowering

acctualy did, run a humidifier this spring as we had some very dry air from the long winter, even I had problems with dry skin, had a RH on 28-32% now with the humidifier running I have nice 42% (in flowering)

ill have to try that. im doing 12/12 from seed, my humidity is at 28%.