When You Turn On Ur Exhaust Do The Temps And Humidty Change Immediatly Or Does It Take Some Time? Wasnt Sure Exactly How It Was Suppose To Work...was Thinking Of Adding Another Exhaust B/c I Dont Not See A Temp Change Immediatly, And I Only Have Cfls Now...the Temps Arent' High Around 76-82, But Wondering What About When I Hook Up The 400hps..please Let Me Know. Thanks

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This is a great question. This is one of the most misunderstood ways to creating stretching. The greater the difference from your day time temps to your night time temps, the greater your internode length will be.
You want to keep the difference under 12 degrees.

There is a rule of thumb, that says to expell and replace the air in your grow room, like every 5 minutes or so.

So far as humidity, around 70% for early seedling development, 55-70% during veg and 30-40% during flower.

Here's a link for you to figure out how much fan you'll need to cool your new light.
I hope this helps you.
Peace

So Are You Saying That The Temps Should Be 12 Degrees Diff At Night? My Babies Are Only 15-18 Days...i Have Noticed That My Grow Area Is Always About 5 To 6 Degrees Diff Then The Room I Am Exhausting From And Thats With Cfls...i Have Around 110 Cf In My Grow Area And Currently I Have A 4' Carbon Filter W/ An Inline 170cfm Fan. I Wnet With This Fan B/c The Max Size Of Fan For My Carbon Filter Is 200cfm..it Seemed Like The 6' Carbon Filter Was Huge And The I Was Thinking The 440 Cfm May Be Overkill...what Would You Suggest?

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With You Calculations My Temps Should Be Around The Same...

(400 X 3.2) / 170 = 7.5

74 + 7.5 = 81.5 Degress..is That A Safe Temp?

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Hey, No, I am saying that you want no more than a 12 degree difference. The closer the temps are, the better.....less stress.
There is a formula in my signature with a formula to figure out how much cfm you'll need to push. How to cool your grow room.
Yes, that's safe. if you want to nit pick, another 5 degrees lower would be nice, but what you got will work for sure.
Peace.

Oh Ok Great...yeah My Temps Usually Stay Around The Same Day Or Night, Just A Few Degrees Diff At Night So I Should Be Good. Plan On Putting The 400hps Is There Today And See How The Temps Work. I Am Going To Run It Without The Exhaust Or Anything At First And See How It Works...will Let You Know The Results...take A Look At My Grow...i Think Its Gonna Turn Out Nice...

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yea nice like a desert. even 400 watters dish out the heat. they will dry your room even i a 10X10 room it will be too hot.