Questions about light leaks and heat

Hi All,
I have a few concerns about my veg area which is a 2x4 cabinet that is 3 ft high and in an upstairs room in my house. It's fairly hot where I live averaging over 100 these days and since it's the upper story things tend to get hotter up there.

I have 4 T5 bulbs in there which is also contributing to the heat as well. I have a small AC in the room so it's pretty easy to keep the room temp comfortable and with enough fans etc...i can keep the cab at about 80 degrees most of the time. The bigger problem is that when I close up the cab at night (12:00 AM light off) I just cover it with a heavy moving blanket but the lights turn back on at 6:00 AM, I usually don't get to it for a few hours and by that time it's can get up to 86-90.

I have 3 6" fans inside the case and one is right in front and practically mounted to a 6" intake duct. the other two are circulating air and are low as to push up the heat . Above my lights, I have an exhaust duct with a 6" in-line fan on it that moves 250 CFM sucking the hot air from the light upwards and out.

normally during the daytime when the light are on I just have the front open or I hang a strip of mylar which leave some room at top and bottom for circulation but even that brings up the temp.

My first thought was that I need to get something lighter weight to cover the cab at night figuring a lighter weight fabric or something wouldn't retain as much heat. but light-weight and opaque to block the light makes it a hard thing to find. I'm wondering if i were to take some green plastic (say a cheap plastic table cloth or double up a green sheet) and put that over at night it would help reduce the heat and the green light coming through would not bother the plants. Could that work? I've been reading around and I see people that cover a flashlight or headlight with green plastic to enter their flower tents after dark so why not a full green "door"

The other thought I had was to have some glass cut the size of the box and affix it just a few inches below the T-5s to separate them from the plants and make it easier to that exhaust to pull the hot air from the lights.

The only other thing I have considered was taking two 180 LED UFOs from my flower tent and switching them with the T-5s since they're probably cooler. That would leave my flower tent with a platinum led 300 and (2) T-5 fixtures 4' with two HO54 bulbs each (of course i'd switch those to a red spectrum. I figured I could hang the T-5 slightly to the sides of the plants to penetrate the lower parts of the flowering plants if I went this route. My flower tent is in the basement which stays quite a bit cooler.

Any thoughts or ideas would be great! I'll follow up with some pics from my phone

Thanks in advance,
Troy

Not sure why your cabinet leaks so much light. Is it just the corners/seams, can they be caulked or taped?

Also, not an expert but don't think it's that big a deal to have light leaks in a veg cabinet, only flower.

Lastly, it's 6am, get outa bed already.

Wow Troy that's a long read bro. I'm too lazy to read all that so I skimmed through. Don't worry too much about light leaks in veg. I've never had a problem just turning my lights off for six hours and leaving the tent or closet door open.

nomoresnow said:

Not sure why your cabinet leaks so much light. Is it just the corners/seams, can they be caulked or taped?

Also, not an expert but don't think it's that big a deal to have light leaks in a veg cabinet, only flower.

Lastly, it's 6am, get outa bed already.

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LOL...oh come on...i'm up by 8 or 9...not like i'ma hunter of farmer. (at least not by trade)
It's not so much leaks as much as I haven't a door on the box and i just cover it. The cover is insulating due to the thickness and making things hot.

got to be honest with you Troy, your setup don't sound very effective

your outside temps are 100c and you have 6" fans pulling hot air in and out the room, the fans are producing a lot of heat without the lights
and replacing the air in the room every few minutes so what chance has the ac got ?

why not try getting a 4" fan (intake air) and 5" fan (exhaust air) and a timer so the fan switches on every 1hour for 15 minutes to replace the co2
this way the Ac can keep the temps in the room just right 24/7

Gary Goodson said:

Wow Troy that's a long read bro. I'm too lazy to read all that so I skimmed through. Don't worry too much about light leaks in veg. I've never had a problem just turning my lights off for six hours and leaving the tent or closet door open.

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Hey Gary, Yeah sorry about the details but I didn't think pics would do that much justice since we all know what a 6" duct looks like or a 2x4 box. I did take a few snaps of the setup that I'm going to upload from my phone now. Thanks for the input thought dude!

jacksthc said:

got to be honest with you Troy, your setup don't sound very effective

your outside temps are 100c and you have 6" fans pulling hot air in and out the room, the fans are producing a lot of heat without the lights
and replacing the air in the room every few minutes so what chance has the ac got ?

why not try getting a 4" fan (intake air) and 5" fan (exhaust air) and a timer so the fan switches on every 1hour for 15 minutes to replace the co2
this way the Ac can keep the temps in the room just right 24/7

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hmmmm...maybe I didn't explain it well enough. the AC has no problem keeping the room nice and cool. it's more about the heat from the lights. lights off I'm sure the temps are 78 degrees (or lower). The 6" fans are inside the cab and serving as circulation and movement. one of them if Drawing air through a 6" intake duct about 3' long and positioned in the coolest part of the room. in fact, a thermometer set next to the intake duct reads in the mid-high 70s due to the room fan and AC blowing right into that corner. The inline 6" is on top pulling out hot air from the lights. if not for the top fan pulling out the upper air, it would probably be even hotter. So, the problem lies with the heat of the lights, I believe, and particularly early in the AM before I can get them uncovered by the heavy blanket.

Here are a few pics of the setup...

Here's the full view...AC on the left and tower fan are pointing toward the box. The dark right corner to the right of the box is here the intake duct is and it's very cool in that corner.

over view of the box....two 6 inch fans on the right side blowing slightly upward (one is blocked by the plants.) the one on the right is drawing intake from the room. From here you can see how maybe a slice of pane glass under the light might bock the heat and let it be sucked out more effectively because of the smaller area. The 4" duct on the left is just an old one that I stuck into the AC vent for the central air and covered around it with blankets. Not sure it[s doing anything but figured it couldn't hurt since the air is on most of the time these days.

Here is the exhaust duct from inside the box....you can see it's positioned right above and between the two dual T-5 fixtures.

Here's the the exhaust duct from the outside top of the box...this vents to the outside though a window along with the AC.

Not sure if any of this helps but thought I'd throw them up anyhow.

that makes a lot more sense as I can see you set up now lol
looks really good

can you pull the cab forwards 2-3" and cut a 2ft x 4inch strip out the back / bottom of the cab as this will stop most the light leak and keep the cab cool, then you can put 2 doors on the front and reflect all that light back in the room as the blanket could absorb the light and turn it into heat (wasted light you will need in flower)

talking about flower, if your flowering in the cab you need to do it soon (if your not growing autos seeds) as you will run out of space

glass will absorb too much light

Thanks...no this is just a veg cabinet...my flower tent is in another spot and is larger and cooler. It has LEDs.

So youre saying to cut out most of the back wall? 4X2 would be about 2/3rds of the back wall.

As far as the blanket absorbing and turning the light to heat. It should be mention that even with the blanket off i sometime hang a strip on mylar across the front which has a few inches open at both the top and bottom for circulation and that makes the temp sore too.

Oops my bad...just noticed you said 2 foot by 4 INCH. still not sure how that differs from the two intakes one 6" with fan and one 4" passive. Wouldnt that be the same as just adding another passive intake? I mean when the light are on the whole front is open. Hmmmm....

What about the idea of switching the T-5 and using the two LED UFOs (180w each) with the veg and putting red bulbs in the T-5s for side lighting in the flower tent?

Troy622 said:

Oops my bad...just noticed you said 2 foot by 4 INCH. still not sure how that differs from the two intakes one 6" with fan and one 4" passive. Wouldnt that be the same as just adding another passive intake? I mean when the light are on the whole front is open. Hmmmm....

What about the idea of switching the T-5 and using the two LED UFOs (180w each) with the veg and putting red bulbs in the T-5s for side lighting in the flower tent?

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the heat problems not when you have the blanket off but when its on and you want to reflect all the light back on the plants,
you want to reduce the light leak at night too ?

a long passive intake in the middle back of your cabinet will give your plants a lot of fresh cool air and help to cool the cab down
24" x 4" = 96" with no ducting to reduce the air flow, could go 3ft x 5" just to make sure

6" hole and a 4" hole is not even half the size and i don't know how well the desk fan works with ducting

t'5 as side lights is a really good ideal , seen a lot of growers use them

two LED UFOs(180w) sounds good but TBH i have never used them, If your going to use 400w's of light
I would go for a 400w hps over UFOs

Yeah the wife isnt going to be up for me buying more lights right now...lol. What i have now are 2x 180w LED UFOs, 1x Platinium LED300, 2X 4' DUAL T-5 fixtures with two bulbs each equaling 108w each (HO)

So if i swithed the UFOs and the Florescents, i would have 360w in my 2x4 box and 516w in my flower tent which is about 4x4 as i mentioned i would probably hang the T-5 horizontally just below or right at the canopy line angled down a bit for deep penetration.

Today im giving a similar idea to yours but in the front. I hung a piece of reflective mykar across the front with a few inches open only at the bottom.

Troy622 said:

Yeah the wife isnt going to be up for me buying more lights right now...lol. What i have now are 2x 180w LED UFOs, 1x Platinium LED300, 2X 4' DUAL T-5 fixtures with two buld each equaling 108w each (HO)

So if i swithed the UFOs and the Florescents, i would have 360w in my 2x4 box and 516w in my flower tent which is about 4x4 as i mentioned i would probably hang the T-5 horizontally just below or right at the canopy line angled down a bit for deep penetration.

Today im giving a similar idea to yours but in the front. I hung a piece of reflective mykar across the front with a few inches open only at the bottom.
View attachment 3469568

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didn't know you had broght the lights
there good lights so go for it, hanging the t'5 level with the plants is a good ideal

hanging the mykar across the cab is good and it will reflect loads of light back on the plants but its going to leak some of light back in the room as its at the front of the cab

could be a problem at night

I'll see how it goes...it seemed to be a bit cooler this AM than usual but I also had the AC a little lower because it's steaming here the last few days. Yeah, the light i have are what I'm stuck with for now....eventually I'd like to go 100% LED.

one strange thing I forgot to mention last night. When I first set up the big exhaust on the top. I stuck a thermometer in the end of the exhaust hose and it was the same as the room temp even thought it was 3 or 4 degrees higher in thee cab. This was with nothing on the front at all though so maybe that's the key....blocking off the higher areas (where the hotter air would want to go. so it can draw it out in exchange for cooler air from the lower areas (as your good idea suggests!) As for the light leaks if the temp stays and stabilizes, i'll make a better front cover (good old 99 cent store windshield reflectors!) and cut the hole in the back as you suggested originally. Also two of the larger plants are going down to flower today or tomorrow so that will make room for better circulation inside the veg box, no?

that's spot on troy, cool air needs to enter the cab at the lowest point you can and exits at the top, as heat rises.
your right there, more circulation will reduce hot spots in the cab

Holy shit that's a lot of reading for the simplest answer in the world, set your alarm for six, take the blanket off and go back to bed dude.

MoMoGrows said:

Holy shit that's a lot of reading for the simplest answer in the world, set your alarm for six, take the blanket off and go back to bed dude.

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Thanks but I'm 53 years old and probably could have figured that out myself Bro! You try running two business and up keep a home and get out of bed at 5 or 6....I prefer to get my sleep. Maybe i should just toss my timers too and go around to each light and fan to turn them on one by one! LMAO!

I feel you man, my bad. That is exactly what I was doing tho while veggin, alarm at six to open grow room door then back to bed. I give you props for all the good info you shared to get help. The high temps for two hours shouldn't do too much if you are up at 8. A few timesiI've had leave my door closed for four hours after lights on and hasn't been a huge issue. Other than the heavy blanket you can get light plastic from the local grow store that's white on side and black on the other. Its real cheap and should be cooler than the blanket. Table clothes and sheets and stuff will let light through but that plastic won't.

MoMoGrows said:

I feel you man, my bad. That is exactly what I was doing tho while veggin, alarm at six to open grow room door then back to bed. I give you props for all the good info you shared to get help. The high temps for two hours shouldn't do too much if you are up at 8. A few timesiI've had leave my door closed for four hours after lights on and hasn't been a huge issue. Other than the heavy blanket you can get light plastic from the local grow store that's white on side and black on the other. Its real cheap and should be cooler than the blanket. Table clothes and sheets and stuff will let light through but that plastic won't.

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That's what I was thinking (plastic) i was even considering Green so that if any light DID slip through it's not a biggy. I'm not sweating it that much anymore cause after Gary's comments above I did some more reading and seems it's not that big a deal if they get a little light here and there after hours.

My buds are looking a little puney though on my first two completed flower cycles so i thought maybe trying the T-5s in place of the UFOs might give some added Penetration that the LEDS aren't providing them right now. As it sits my flower has the platinum 300 LED centered up with a UFO on two opposite corners (diagonal) angled slightlyinward - total of 660w. Veg has the 4 T-5 54w for a total of 216w