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400W Distance
- Thread starter Bobbo4200
- Start date
As close as possible without burning.. Hold your hand where you want the light to be if its to hot for your hand move it up an " until your OK. I would say 9" with good air movement. 12" without..
if its aircooled,and its a 400, i like to push the limits and go 8-10 inches. thats where im at now with no leaf burn.put your hand under and feel. if its uncomfortable after a minute -no good. as the member said above,take a canopy temp with a laser temp or thermometer.
yeah 84-86 is pushin it- place a fan and have it blow over the tops just under the lights,then measure. should be golden after that with a few adjustments as well.
yeah 84-86 is pushin it- place a fan and have it blow over the tops just under the lights,then measure. should be golden after that with a few adjustments as well.
i keep mine about 12 inches away, not just for the safety of the plants but so that i get a nice even footprint, if i push it closer the edges don't get as much light, though ive gone closer, my cooltube is vented so well the glass barely even gets warm.
rickyjack9
Member
I get plant stress if closer than 24 in. if 1000w needs 40 in, then a 400w at 2 feet is like 4x400w=1600w equivalent. also heat/dry can cause mites I think. I have a sweet dimmable 1000w set at 50% or 500w, im at 2 feet. maybe late flower I will go to 750, then maybe 1000 last couple weeks to finish?! but id be raising light higher then... my .02
M
meowmeowmeow
I hope this helps
I hope this helps
Meow...........
1. What strain?
2. How many days in veg?
3. Did you train, fem, pinch, top any of the branches?
4. Organic, synthetic, combo of nutes?
5. Ambient air temp in enclosed space? How big of a space?
6. Are you expelling the spent air?
7. Using CO2?
8. Container size?
9. HID or MH bulb or combo fo both?
10. Light penetration to the bottom half of the plant?
11. E=MC2
Honestly there are so many factors involved, so IMHO one never knows until they document and do it a couple of times.
Even then it can vary.
I've done 1k w HID and as little as 300w LED with there being a HUGE difference in final take (1# vs 4 oz. s).
Good luck
I hope this helps
Meow...........
1. What strain?
2. How many days in veg?
3. Did you train, fem, pinch, top any of the branches?
4. Organic, synthetic, combo of nutes?
5. Ambient air temp in enclosed space? How big of a space?
6. Are you expelling the spent air?
7. Using CO2?
8. Container size?
9. HID or MH bulb or combo fo both?
10. Light penetration to the bottom half of the plant?
11. E=MC2
Honestly there are so many factors involved, so IMHO one never knows until they document and do it a couple of times.
Even then it can vary.
I've done 1k w HID and as little as 300w LED with there being a HUGE difference in final take (1# vs 4 oz. s).
Good luck
Last edited:
OranguTrump
Crotchety Old Crotch
I use these charts for reference
Budgrower4life
Member
Hi can I ask what temp the canopy temp should be. If I use a laser temp gun
Thanks in Advance.
M
meowmeowmeow
My canopy with exhaust fan kicking on every 30 minutes in the 18 hr cycle keeps it @ approx 75-85 C when lights are on.
RH stays around 25-40% average
Slight variance in both when they get watered.
2 300w Leds and 1 50 W UFO hanging approx 12-18 inches from top of tent.
M
meowmeowmeow
I was off a bit.
The Rh has a large margin of difference as seen. To be positive, I hope the fade of the plants will be colorful unlike what I experience in a more humid environment due to this factor.
Upper
Lower
The Rh has a large margin of difference as seen. To be positive, I hope the fade of the plants will be colorful unlike what I experience in a more humid environment due to this factor.
Upper
Lower
Budgrower4life
Member
I have 2 day old seedlings 16ins away from 400watt metal halide no other
Light I can use..cfl light broke.
Light I can use..cfl light broke.
That is way too much light. You want them to root, not grow at that point. Could fry them from heat also. Many use T5's throughout most of veg and would keep at that distance or more, that early.
Tri_Cho_Me
Member
75-85C or F?
I have been battling heat with an Advanced Platinum P450 & two 50w Single LED's in lamp clips. The P450 is nice, but the footprint is tiny in my 2x4x7 tent. So I added the two single bulbs on the edges to help, but they push my temperature into the mid to upper 80's. 88 at one point. Without going over 88, what sort of damage, if any do you think is occurring? THC loss? Flavor loss? Or is 88 not all that extreme? Doesn't seem like it would be. I mean, Mother Nature as we know goes well above that. Just curious what your thoughts are!
Tri_Cho_Me
M
meowmeowmeow
@Tri_Cho_Me
My bad Fahrenheit ..... stupid American.
If too hot your plants will not fully develop from what I have seen.
Fix it quick IMHO.
Not to highjack the thread........but do you have an exit air strategy a la a fan expelling the air from the tent?
It's 9 F outside here now and approx 66-68 F in my house, so I don't have many issues with heat like I did in da South.
My bad Fahrenheit ..... stupid American.
If too hot your plants will not fully develop from what I have seen.
Fix it quick IMHO.
Not to highjack the thread........but do you have an exit air strategy a la a fan expelling the air from the tent?
It's 9 F outside here now and approx 66-68 F in my house, so I don't have many issues with heat like I did in da South.
Tri_Cho_Me
Member
@Tri_Cho_Me
My bad Fahrenheit ..... stupid American.
If too hot your plants will not fully develop from what I have seen.
Fix it quick IMHO.
Not to highjack the thread........but do you have an exit air strategy a la a fan expelling the air from the tent?
It's 9 F outside here now and approx 66-68 F in my house, so I don't have many issues with heat like I did in da South.
Yea, I have a 2x4x7 tent with a 4in. intake and 6in. exhaust with a carbon filter. My house is 68 as well, but in that tent, with those lights, the temperatures can creep! I repositioned the two fans I have at the bottom of my tent to blow uo and through the canopy and I think it is helping quite a bit. I might also try lowering my home thermostat during the peak hours of the tent to see of that helps at all.
Tri_Cho_Me
