Grow tent heat question

I plan to use a 4x4x7 ft grow tent and my question is:

How much more will i need to vent a 400 watt hps/mh system with a tempered glass lens if i am already venting the tent with an inline fan that pushes 250 cfm and a box fan for the plants at the bottom of the box to have air blowing over the plants.

well i used a 171 cfm inline fan for a 600 watter and it worked fine, also have the 600 in my closet with no inline fan just 2 house fans and it works great

Chronnik said:

I plan to use a 4x4x7 ft grow tent and my question is:

How much more will i need to vent a 400 watt hps/mh system with a tempered glass lens if i am already venting the tent with an inline fan that pushes 250 cfm and a box fan for the plants at the bottom of the box to have air blowing over the plants.

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If your using an air cooled hood, no further venting should be required. I am running a similar set up and my temps never got over 87 even in the summer.

How is the air flow routed?

CK

87 is pretty high u should try to stay below 85 if not 80, but i know this is hard,

mcpurple said:

87 is pretty high u should try to stay below 85 if not 80, but i know this is hard,

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I would agree with you, but this was mid Cali summer, valley temps, 98+ degrees outside, the kind of weather you learn to despise while on an 18 hour cycle.

I aint gonna split hairs over 2 degrees when considering all the info.

CK

captiankush said:

If your using an air cooled hood, no further venting should be required. I am running a similar set up and my temps never got over 87 even in the summer.

How is the air flow routed?

CK

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Well im not to sure how i want to set this up since i dont have it all here yet. Basically what i was planning on doing is hooking up the inline fan at the top of the tent that sucks in the air of the tent with ducting that leads to a carbon filter that filters back into the tent. Then having a box fan at the bottom for air flow over plants. The hood isnt going to be cooled directly, but has a heat shield on it or tempered glass lens as it is called. I guess my question is will i need to cool the light more or is what i have in mind good. Sorry for confusion i really dont know how to word things well.

Chronnik said:

Well im not to sure how i want to set this up since i dont have it all here yet. Basically what i was planning on doing is hooking up the inline fan at the top of the tent that sucks in the air of the tent with ducting that leads to a carbon filter that filters back into the tent. Then having a box fan at the bottom for air flow over plants. The hood isnt going to be cooled directly, but has a heat shield on it or tempered glass lens as it is called. I guess my question is will i need to cool the light more or is what i have in mind good. Sorry for confusion i really dont know how to word things well.

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I got you. Just an idea but you may want to consider routing things so that you dont have to take up space with your carbon filter inside your tent., good idea to keep you fan out too since that will make heat as well as take up room.

My philosophy is I want as much space for my girls as possible, that means anything I can keep out of the tent I do, including exhaust fans. Cooling the light will really drop your overall temp and if you run it so the air is pulled from the tent, through the hood and exhausted through the carbon filter, you can get away with passive intake, since your tent should have air vents on the lower section and pulling that much CFM from that small of space will result in a vaccum, you should get plenty of fresh air.

CK

Ahh ok so basically your saying have the fan on one side of the light sucking air out through the carbon filter on the outside of the tent. As for the box fan im actually planning on setting it up on top of the tent near a vent hole to get fresh air in the tent but i want it on the inside so i can have air flow over the plants. i might later on cut a hole in the bottom of the tent and vent fresh air in with another inline fan same 250 cfm.

Chronnik said:

Ahh ok so basically your saying have the fan on one side of the light sucking air out through the carbon filter on the outside of the tent. As for the box fan im actually planning on setting it up on top of the tent near a vent hole to get fresh air in the tent but i want it on the inside so i can have air flow over the plants. i might later on cut a hole in the bottom of the tent and vent fresh air in with another inline fan same 250 cfm.

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In my setup i have 6" clip on fans as well as a 6" floor fan to keep the air moving over the girls...I dont have any current pics in my new log but you can check out the set up in my previous log, here:

https://www.rollitup.org/grow-journals/252886-captians-log-3.html

CK

Thanks for all your help man and your patience. Here is a sketch of what i plan to set up. make it a lil easier to understand what im thinking. The red in the picture is the inline fans, the box fan is on the top left blowing down and the carbon filter is blue. You will notice the black lines that are trying to indicate air flow. The ones by the light are going up into the light and out into the carbon filter tunnel. The fan at the bottom is just bringing fresh air in. The box fan may switch to clip fans as u have, but that just blows air across the girls. I Also had one more question to ask you. What light setup are you using. Because i am looking for a somewhat cheap 400 watt hps set up with the hood like yours. Im guessing that it has the tempered glass on it as well.

Chronnik said:

Thanks for all your help man and your patience. Here is a sketch of what i plan to set up. make it a lil easier to understand what im thinking. The red in the picture is the inline fans, the box fan is on the top left blowing down and the carbon filter is blue. You will notice the black lines that are trying to indicate air flow. The ones by the light are going up into the light and out into the carbon filter tunnel. The fan is just bringing fresh air in and the box fan may switch to clip fan as u have, but that just blows air across the girls.

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I am repping you just for the pic...classic!

I see your plan now, looks pretty good to me airflow wise. Give some thought to the weight of the fan and filter, on top of the tent like that would make me nervous,

CK

Lol thanks man i edited my post but i didnt see u had replied already, anyhow i was asking about your light system or if u know where i can get a good one or a good price range because the one i was planning on getting someone just told me was way to pricey for 400 watt setup. Guy was gona charge me $400 for 400 watt HPS/MH switchable magnetic ballast with a air cooled setup and a heat tempered glass heat shield with a 1 year warranty. Any how i wasnt planning to leave the filter/fan on top of it lol just didnt have room on the paper to draw my whole room lol. Thanks again you have been a big help and when i get everything setup ill def. be posting it back up here with real pictures not some half assed pic i just drew. Toke on man!!

Exhausting through the filter instead of sucking with it dramatically reduces it's lifespan. Dirty air should enter the filter through the large pre-filter first, then be funneled down tighter and tighter into the core.

http://www.progressive-growth.com/growrooms/2lightaircooled.htm

Chronnik said:

anyhow i was asking about your light system or if u know where i can get a good one or a good price range because the one i was planning on getting someone just told me was way to pricey for 400 watt setup. Guy was gona charge me $400 for 400 watt HPS/MH switchable magnetic ballast with a air cooled setup and a heat tempered glass heat shield with a 1 year warranty.

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My apologies, I was really medicated.

$400 is ALOT for a magnetic ballast set up. I paid less than that for my setup and its digital ballast, air cooled, etc.

HTGS has good deals on light setups, I just ran the numbers on a 600 W, digi ballast, air cooled hood + hangers and it was under $400 WITH shipping.

CK