When can I move light closer?

[Bree1978]

I made a new thread, because I don't know when it will be read...when can I move my light closer...I've been flowering for 7wks under CFLS' (approx. 19000lu) and just moved them to a HPS (approx 50000lu). I started them with the tops 2ft away, today...temp there is 78F...there were in higher heat before I moved the room and lights. They look good and all, just want to know if that was the proper height to start with...to me, it seems I can put my hand much closer to the light. (about 12 inches from hood it is about 88 with door closed, open it would be a little better)...

Well sorry for more q's....don't have much better than stress about them with this snow...lol...Thanks! :jointsmile: Bree

[dusto2k3]

LoL, its horrible to be stuck in a room with a bunch or plants.

My plants range from 18-14 inches(1KHPS). The closer the better., put your thermo at canopy height so you can gauge the temps at the canopy level.

[Bree1978]

78F is canopy height right now, 2ft away from hood...sorry if I did not put that clearly...But from what you are saying, go ahead and move it a little closer, say 6 inches? I only have 4 hours til' nite nite, so I could probably catch it quick. B

[dusto2k3]

woah, 4" is close. I hear 73-78 is optimum, but if you can keep it cool, 6" would be great..

mine have gotten in the 90's too(summer), but i'm sure it hurts the yield.

[Bree1978]

? I'm 24 inches from top right now.....? I wasn't going to go to 4inchs from top...lol. where did you get that? I'm 24 inches now, go ahead and try 18? still, laughing, although I might have read it wrong, i've had a few....lol

[Bree1978]

four hours was what time the lights go out......lol

[dusto2k3]

LoL, now im laughing..yeah try 16-20 inches, maybe even 18...

Just check the temp after you move it after about 30 mins, to let the temp even out, a good scientest would wait about an hour.

[Bree1978]

:jointsmile: Bree

[dusto2k3]

Just check the temp after you move it after about 30 mins, to let the temp stabilize, a good scientest would wait about an hour.

[Bree1978]

Done, noted, and thank you, :jointsmile: Bree

[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.:o

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/100718-mrs-greenjeans-first-ever-grow-2.html#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.

[dusto2k3]

with good vent, i would think your temps should rise only like 2 deg. or close to that.400HPS)