Heat Problem

jollygreen said:

Well it is just hitting spring and its still a little chilly outside... so I imagine in about 3-4 weeks when its 30-40 degrees hotter outside regularly that my room will heat up a bit more too, so I don't want to be in the position of it hitting and sitting at 90+ degrees in my grow room, but maybe I'm being paranoid. Also I have to hook up the exhaust to the hood which like unlucky said, will probably bring down the temp quite a bit.

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Well the question is what is the current temp of the air going in the grow room? If you are forcing air in from your home I'm sure it's near 70 degrees, once spring comes your house temps shouldn't change too much and when summer hits a/c of course. As long as you can exhaust hot/humid air outside of the house the indoor temps will be easy to control as long as you have proper ventilation and circulation. Am I missing it, where is your osculating fan? Definitely a must.

Rancho Cucamonga said:

For veg it isn't the end of the world but once flowering and even in veg, 75-80 is where this plant grows the best. Unless you are using CO2 85 is quite high for a indoor grow. The potency and yield at temps under 80 is positively noticeable compared to temps over 80. I started with high temps and tweaked my rooms to be 76-78 day 64-68 night and the difference is all positive.

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The tests that I have seen with atmospheric levels of CO2 and different light levels that photosynthetic production peaks around 85 and 1500 umols of light and does not drop until temp significantly exceeds 35C. That seems to match many of the growing areas whether they are Indica or Sativa.

But I guess differnet indoor envs have different optimums. as you found for yourself.

The oscillating fan is sitting outside the front two doors. Right now I am running 8am-8pm OFF, 8pm-8am ON but I dont know what I'll be doing on the next batch. Eventually I want to install one up in the corner on the inside and just let it rotate back and forth fanning the plants, while still having an in-take and out-take fan, and adjust according to temp, humidity, co2, etc.

But there are a lot of things I want to do, just don't have the $$ to do it all yet.

If cooling gets to be any harder it WILL be an issue. We are 3 days into spring unless you are an Aussie. CO2 gives you 7-10 degrees extra and Silicon supplements are good for dealing with heat and water swings as well as make production increase. I put another exhaust source and I could stay in the 70's and get the lights closer. Since you can procure a variety of strains, find one that does well in the heat. Put intakes on each wall to draw more cooler air in. Plumb the hood so it pulls cool intake air over the bulb and directly out with as few curvatures in the ducting as possible...make it a closed system. Make the floors white and hang a small oscillating fan so the plants are doing a gentle shimmy at all times, you will get a woodier branch and your buds get heavier because of that. It looks like a great start. Heat is one stressor that I don't put up with.

So my temps are usually around 78-80 right now.. occasionally go up to 82.. but thats without my intake fan going just my outtake, so we'll see.... I've been wondering lately, if heat becomes a problem once its a completely sealed environment, if I could hook up some type of small refridgeration unit up to my intake, so it pulls air through a cooling unit that cools all the air slightly as it passes through.

Also, I was wondering if you guys could weigh in about when I should harvest.. I'm on like day 45 of flowering right now. I started with 10 bag seed and ended with 2 confirmed females (4 were male, 4 were herm)... And the herms managed to slightly pollinate the girls before I cut them.. Like they popped like 1 nut all over my girls each, before I immediately realized it and choppped them. so like 2 pollen sacks exploded all over their faces and got em pregnant. I expect some seeds, just not sure how many to expect.. tho time will tell, I can definitely see a few developing already. So when would you think I should harvest?

Something else to consider in your duct work is that any 90bend reduces your fans efficiency by around 20%.

I see alot of bends in your ductwork.


Have you tried to make them as straight as possible without any bends?

This alone could see you hold steady at 75f.

Also make sure you aren't dumping the air from your grow into the room where the grow is located.

For eg

Tent in a spare bedroom exhausting into the spare bedroom. Then gets sent back into the tent to recirculate and get warmer then repeats.

Ballasts inside the grow area will increase heat.




J

jollygreen said:

I just finished my grow room. I started with 10 bag seeds but due to 8 of them being males/herms I am down to two confirmed females now. I have them under a 600w MH because my HPS burned out and I'm too broke atm to get a new one. Anyways, I just installed what I thought would be a pretty ballin ventilation system. It's a 4' x 4' x 6' (WxLxH) box. I used a hole saw to drill two 6" holes. One near the bottom on the side for intake, and one above the hood for out-take. I used a 6" in-line duct fan for the intake and an 8" inline fan for the out-take.

It was 84 degrees in there (usually hovers around 78-80), and after I turned both the fans on and closed the doors it went up to 85 degrees lol. I was really thinking that would be enough ventilation to decrease my temp by at least 5 degrees but it doesn't seem to be working. Any suggestions for improvement? Here are some pictures of the set up:


I know the humidity is insanely low, I just don't have $ atm to buy a humidifier, but it is coming soon.

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Looking at your pics I see a couple of things, first those fans are not inline fans they are booster fans. Boosters rely on the forced air system they were meant for, using it in your situation I would think you aren't running the cfm's you think. You also show a restriction on one of the fans, reducing or restricting one size on a booster fan results in a 60% drop in your volume of flow or more. Flex hose is also robbing you of valuable cubic meters.

Try reducing the restrictions by using less bends and solid tubing. The best thing would be to buy an actual inline fan, charcoal filter and maybe even a portable air conditioner...summer is on the way. I understand cash is low but think about your set up and you can solve some of these issues with nothing but inginuity and elbow greese.

Good Luck and buy the way I wouldn't worry about your low humidity, running at 15% all winter here and its great! Just be ready for more watering because when its dry they are thirsty. The lower the better in my books.

My ballasts arent in my tent so thats good. As far as the ducting, there is only one 90 degree angle.. there is another one that's close to 90 degrees but not quite.. the rest of it is pretty straight for the most part I thought. And it pumps the air into my attic/crawl space above the bedroom which is just insulation on the ceiling boards, but its an old house and the roof above isnt insulated. I figured the hot air would went into there and then slowly seep out of the roof of my house. I also throw some oNA gel up there every day because I dont have my carbon filter up yet.