When can I move light closer?

[invision]

bree put the backside of your hand under the bulb, move it away slowly until its warm and not hot, put your plants that close

my plants are about 2" from the hps, yes 2 inches.

[Bree1978]

Invision, I did say that didn't I? HA HA, no, I just though it, stoner me, drunk me, ... I can get quite close to my lights without the backside of my hand getting hot. I will search it out, I'm letting the canopy get a proper reading....I moved it 18" inches from top cola. It is still 78, but I've been fussing...lol....B

[invision]

drinking is bad mmmmkay!

[latewood]

Good, then once you determine the height you can safely put your light over canopy...take note. as plants grow, keep light safe distance. Invision said it well. I say it like this.

put hand at top of canopy. lower light until you cannot stand the heat for a full minute...once that distance is determined...raise lamp 2" and keep that distance consistent throughout grow...peace

p.s. always have a fan dedicated to the airspace between the lamp and canopy, and you will be safe. Another circulating fan is required also.

[Mrs. Greenjeans]

Sorry for jacking your thread Breebaby, but I need to ask Latewood something.

Latewood, when I had my light that close to my plants, my temps at canopy level were waaay too high. Like 84, sometimes 86. What's your advice in that sitch? Oh btw, this is a 400W hps. I have an intake fan moving 45cfm, an exhaust moving 92cfm, a dual fan blowing between the light and the canopy, and a large turbo floor fan blowing angled upward to blow on/up the plants. Still my temps were too high. I finally got them to settle to 81 by raising the light 12 inches. It's now 17-20 away from canopy. Your thoughts?

[latewood]

well sounds like you need to ventilate. Your canopy temps are not relative height of lamp, as long as they are not burning. what is overall room temp?

[Mrs. Greenjeans]

Overall room temp is 80F, room is 5.5'x3'x6.5'=107.25cf. Actual space used for grow is 4sf. Intake fan 45cfm, exhaust fan 92cfm. Door left open.

[dusto2k3]

I would get a bigger exhaust fan. Is the exhaust being venter in the same room as the intake? What is the ambient temp outside the grow room?

[Mrs. Greenjeans]

I would get a bigger exhaust fan. Is the exhaust being venter in the same room as the intake? What is the ambient temp outside the grow room?

The intake is inside a windowseat that draws partially on outside air. The exhaust is vented into my bedroom, where the ambient temps are usually 75-80. I don't know because I moved my thermometer into my grow closet

Look at these pics.
http://boards.cannabis.com/grow-log/...ml#post1236752

[dusto2k3]

yeah, i use a 1KHPS and with 192cfm exhaust (4'x4'), i see ambient temp in the grow room rise abour 4-5 deg. higher than that of the outside room.