Question about shutting off lights during flowering.

Is it okay or is it bad to shut my lights off for 5-10 min every 2-4 hour or so during my 12/12 flowering cycle? My room gains about 1.5 degrees an hour or so, and If I could flush the heat out with just cold air, it would be great. Any thoughts would be appreciated. Things I think of would be heat stress, but I only want to drop it to 65 so. Thanks for your time :0

You can't deal with a heat problem by shutting off lights. More cold air from outside or AC, and a better way to evacuate hot air from the grow area is what you need.

Is it okay to do for a few nights? I cant buy or fix this ventilation issue as of now. I read that hormones take 2 hours to convert, so I guess It shouldnt hurt them to take a 10 min break once a night. Any feedback appreciated. Thanks

you might just stress them out with doin that. thats how hermies are born you know
you aint got a fan or nothing?

im not sure the bulb will like all the onning and offing...imho

You can check out my grow in my sig. Ive been battling heat issues this whole grow. 4000w is alot to deal with. I dont have the funds or equipment. The room slowly gains about 1 degree an hour and I dont want it sitting at 92. I will figure out something, rent is just due soon, and I have nothing extra to spend so.

4000w shit.. wish i had your probs..

LSDreamer said:

You can check out my grow in my sig. Ive been battling heat issues this whole grow. 4000w is alot to deal with. I dont have the funds or equipment. The room slowly gains about 1 degree an hour and I dont want it sitting at 92. I will figure out something, rent is just due soon, and I have nothing extra to spend so.

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Kinda sucks man, after all this money its comming down to heat. I need another 500 or so to fix it IMHO, and I just dont have it for a week or two. So I need a short term, short of dimming the lights.

??? wait WHY you got 4000 W of light?! how many plants you growing? 600 ?
just go buy a oscillating human fan and direct it towards you bulbs. 10 bucks tops

If your grow area has a door or a window you could try leaving one of them open a crack in order to let in fresh air from another area. Another thing I tried were foundation vents. You can buy them at just about any hardware store. Just install them above your lights and it will help with your heat problem. Plus they can be adjusted to how much airflow goes in and out. Very inexpensive, only about 2 or 3 bucks.

Only growing 17 plants right now in flowering. Plan to move up to 30 after this run. I like full canopy coverage, I train my plants so they get most light possible. I have 3 16" fans in the room, an 8" inline for cold fresh air, 6" exhaust. I think my exaust is my bottleneck. I want to get a 8" but I just dont have the money for it. Ive spent most of what I had saved to get to where I am right now so.

I think he means 400 not 4000. Not only do you not want it at 92, you don't want it at 82. I think the hard fact is that when it is as hot outside as it must be, and you can't supply lots of AC, then you simply don't have a suitable growing environment for this plant. It's why I don't grow in the summer.

400 w ? on 17 plants?
you should just grow outdoors at summer.problem solved

No, I mean 4000, hence the heat issue. And I realize it is running hot, why I wrote this post. So back on topic. Is it okay for the plants to deal with a 10 min period of no light during its 12 hours on.

No. It won't help much with heat because not that much will dissipate in 10 minutes. Maybe you should sell a light and buy an air conditioner.

It actually drops it down to 70 in around 5 min. I have a 6inch exhaust attached to an 8 inch carbon filter. And I have an 8" intake fan blowing cold air. I was trying to find a short term solution for the week, I can dim the lights I guess, I just dont want too. 85degrees is supposed to be where plants produce the most efficiently, you start to lose productivity around 90, and it stops at 95 for defense. As I have been told.

Still the same, was just trying to figure out something, oh well.

17 plants. 4000w. how much yeild are you looking for? besides heat issues

man when did you make this discovery? i mean when did you see that the temps were off? you just noticing or what?
if i were you, id take my chances with it being to hot rather than make the whole crop hermies. but thats just me

shouldnt you have a greater exhaust than intake, therefore creating negative pressure.. that might help

Hi LSDreamer, I have quickly read through your journal and watched the videos of your grow room several times. I really don't want to come across as an over opinionated arsehole and I would like to help but I need to be critical to do so.
I hope you take my advice as it is intended one grower to another.


1) Stop over analysing the situation, slow down and think logically.


2) Set your grow room up right first and add plants later NOT the other way round.


3) You are pushing FAR too much light for the floor space and plant numbers you have, you are thinking about the light coverage that YOU can see NOT what the plants see and because you are flowering plants that have a very small overall stature (due to the training) it's more than overkill.


4) In reference to your ventilation problem first.
You should always have more exhaust than intake, ALWAYS!
The fresh/cool air source should come into the room at the bottom, travel up under the plants and out through your filter/exhaust at the top (because hot air rises).
The way you have it set up at the moment the clean air comes in at the top and gets sucked over the parabolics straight back out again through your filter/exhaust so all that your oscillating fans are doing is just blowing the heat from your bulbs around the room.
I suggest removing the intake fan and just have a length of ducting coming from your intake hole at the bottom of the room, round the room to the left along the edge of the floor ENDING just before the centre of the wall pointing inwards (this will provide an up/across air stream with the maximum amount of overall flow). Then attach BOTH fans to the carbon filter for your exhaust (the carbon filter should be higher than it is, tighten those ratchet straps and mount it as high as you can get it WITHOUT touching the roof), You will need to get a Y splitter to attach both fans unless you botch it up with a lot of duct tape (not advisable).
Something like this but in the size you need (it will need a little tape work on one side because you have different size fans).
http://www.ebay.co.uk/itm/Ducting-Y-Splitter-Piece-Extractor-Fan-Duct-Pipe-Ventilation-VENT-100mm-4-/160696436891?pt=UK_Home_Garden_Hearing_Cooling_Air&hash=item256a41089b#ht_545wt_136
I Know it's an English link but you get the idea.


Now you have BOTH fans pulling through that massive filter (also too big for the room size but with 2 fans pulling that will be more efficient in it's scrubbing also) this will create a huge negative pressure within the room dramatically lowering your temps.
I personally don't ever use an intake fan and always run passive (it's only needed in rooms where the negative pressure of the exhaust is not strong enough to provide sufficient clean air resulting in hot spots).

If you do insist on having an intake fan then it needs to be the smallest one mounted on the floor at the wall before your ducting, with your ducting still running along the edge of the room regardless (but this will NOT create enough negative pressure within the the room due to your fan sizes, as you will find out). Shantibaba the world famous master breeder behind the White family advises having the intake 3 time smaller than the exhaust, just to give you an idea.