T5's a few inches from canopy? BUD TEMPS 90+!

joehartley · May 28, 2016

That can't be good for bud development, having lights so close that bud temps get above 96°F. My lights (8 - 4 foot 54 watt T5 mixed spectrum bulbs) are 6" above canopy and temps are high 80's .

8" 380cfm inline intake fan, foliage oscillating fan set on medium speed. 2'x4'x4' grow room, 9 plants from bagseed 2 1/2 weeks into flower. Any more wind and I'd think it would be bad for plants?

How hot can bud temps go without damage/stress/low yield? I must be missing something if everyone has their T5's so close to canopy. :-/

dandyrandy · May 28, 2016

No idea on distance for flouro's but maybe some air movement? Yikes!

joehartley · May 28, 2016

dandyrandy said:
No idea on distance for flouro's but maybe some air movement? Yikes!

As explained...I have plenty of air movement

SPLFreak808 · May 28, 2016

Wait, do you have an exhaust and fan also?

nicougrik · May 29, 2016

id say turn that oscilating fan up high. lots of wind is better than burning your plants. besides, having your plants wave around will strengthen the stems and alow it to carry more bud more esily

joehartley · May 29, 2016

How about some growers using T5s posting the distance from light to canopy AND bud temps!

RM3 · May 29, 2016

I flower with T5's and keep the lights 2 feet away and have canopy temps between 87 & 92

It's just how I roll
.

joehartley · May 29, 2016

RM3 said:
I flower with T5's and keep the lights 2 feet away and have canopy temps between 87 & 92

It's just how I roll
.
View attachment 3694451

Thanks! 2 feet away and still temps in 90s...
Wouldn't this mean those recommending to put fluoros as close as 2 in. have to be frying their buds? I tried using direct fan across canopy and it does lower temps, but it seems all that wind would be bad for plant transpiration?

Guess I'll keep the 6" to 7" distance and keep temps down as much as is practical.

Nice ladies, RM3!

Evil-Mobo · May 29, 2016

I think the bulbs you use will determine the distance from the canopy.....

Talkenlate04 · May 30, 2016

joehartley said:
Guess I'll keep the 6" to 7" distance and keep temps down as much as is practical.
Nice ladies, RM3!

Raise the lights more, or increase airflow, or install an ac. Leaving it at those levels will doom you and all you have done will be for not.

Mr Hyde · Jun 3, 2016

I was curious so I came to check it out, I hope your grow goes well brother!

RM3 said:
I flower with T5's and keep the lights 2 feet away and have canopy temps between 87 & 92

It's just how I roll
.
View attachment 3694451

What is the highest temps you would run those bulbs at? I am afraid of them exploding or what not in heats of 100+, summer is coming so I just wanna be prepared. Sorry not trying to hijack thread.

joehartley · Jun 3, 2016

RM3 said:
I flower with T5's and keep the lights 2 feet away and have canopy temps between 87 & 92

It's just how I roll
.
View attachment 3694451

I can't find it now, but I read that it's not good for bud temps to go beyond 76°F causes buds to be thin and light, not tight and dense.

TankStand · Jun 6, 2016

You want the ambient room temperature to be around 75, directly under the light is always going to be hotter. Put the back of your hand up to where the closet buds are, hold it there for a little bit if it starts to hurt its too close, this is a trick I used to hps so not sure how well it translates to T5s tho.

joehartley · Jun 6, 2016

TankStand said:
You want the ambient room temperature to be around 75, directly under the light is always going to be hotter. Put the back of your hand up to where the closet buds are, hold it there for a little bit if it starts to hurt its too close, this is a trick I used to hps so not sure how well it translates to T5s tho.

That's the biggest problem, since it's in an out-building I can't get the ambient temp below 82 (and it ain't sweltering summer yet!) I'm pulling cooler air from beneath the skirted building with a 8" inline 400 cfm fan to keep grow room in low 80's. Lights any closer than 4" and bud temp is over 90. At 4" with 82 ambient temp bud temps are high 80s. It doesn't burn my hand though. Guess that will have to do. I can't air condition the building.

HansBud · Jun 8, 2016

i had the same exact problem with heat and ended up getting leds for this reason, I now do not have to worry about heat at all and plants are happier than ever

TankStand · Jun 8, 2016

So maybe a dumb question but are your lights on during the day, because if they are change it to being on at night, much easier to bring down temps at night then during the day, at least for me. Other then that the only option I can see is using LEDs as they are cooler than T5s I believe.

joehartley · Jun 8, 2016

TankStand said:
So maybe a dumb question but are your lights on during the day, because if they are change it to being on at night, much easier to bring down temps at night then during the day, at least for me. Other then that the only option I can see is using LEDs as they are cooler than T5s I believe.

Thanks, I've been gradually switching to a nighttime light schedule. Problem with that is getting up so early to water/feed my girls when lights come on at 4 am!

mauricem00 · Jun 8, 2016

joehartley said:
How about some growers using T5s posting the distance from light to canopy AND bud temps!

I run my T5s about 6-8 inches above the canopy and only have a fan in my grow room. canopy temps are only about 3-4 degrees above ambient. perhaps a cooler or A/C in your grow room is needed

WorktheSystem · Jun 11, 2016

Here's a pic of the height of mine. but i'm in a basement, the intake is probably in the low 70's. I'd say I have about 3 inches in some locations, but i have a 400 cfm fan and 2 fans inside. Just curious but do you have a digital thermometer sitting directly in the light? I noticed with mine that it's more accurate if I put it under a little shade cover, otherwise the plastic lens on it kind of bakes the thermometer a little and gives false readings. my temps are usually in the low 80s

Bubblin · Jun 11, 2016

imo toss a fan or two up blowing across the actual tubes, just above the plants. 2 fans blowing across them, 2 fans pulling the heat away on the other end of the fixture.

Although with 82 ambient you'll prolly want an AC anyway.

T5's a few inches from canopy? BUD TEMPS 90+!

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