96"x48"x80 Grow Ventilation Help!

[KnottyDread]

SUP YALL. So i have a 96"x48"x80" tent. For lighting i have 2 1000w Led(label says) and 1 200w led and one 400w led. I have a 240cfm exhaust nd about the equivalent for intake. Do you guys think ill need more exhaust or i should be alright??
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• KnottyDread
• Oct 14, 2020

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• KnottyDread
• Oct 14, 2020

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• KnottyDread
• Oct 14, 2020

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• KnottyDread
• Oct 14, 2020

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• KnottyDread
• Oct 14, 2020

 

[TorturedSoul]

At only 18.59375 watts per square foot of (realistically) mediocre LED light, what you'll need more of, more than anything is more light. And that's assuming that you're planning to grow autoflowering strains and, therefore, will be running your lights for at least 18 hours per day during the flowering phase. If your plan is to grow photoperiodic plants... double what you've got and then add some more.

You've got a grow space volume of approximately 213.3 ft.³. That's less than the rated flow rate of your exhaust fan, so in theory, you'll be moving as more fresh air through your tent than its volume - which would mean that you'd be fine in terms of simple air exchange. Again, that's in theory; it assumes that the rate you stated is actually its true rate. I don't know the quality of your fan, so I couldn't even guess as to whether that's the case.

Your lights are going to add some heat. Approximately 2,030.224 BTU/hour of heat produced by the light-energy created. Their power supplies will add some more (I have no way to estimate that amount). They won't be the best quality, so they'll produce more heat per rated watt than a top-shelf model, but I doubt that they'll produce enough to keep your house nice and toasty on a 20°F night, lol.

If you have a carbon filter attached to your exhaust setup... That's a restriction. How badly that affects your exhaust fan's airflow is anyone's guess. If it's a centrifugal fan (aka "squirrel cage" fan), like the Dayton blowers used in many HVAC systems, it should not greatly impact the flow (again, depending on quality of the product). If, however, it is an axial-flow fan, like the old box style fans that people without air conditioning used to stick in their windows during Summer and the little fans in the sides of desktop computers, the impact of an airflow restriction on net airflow can be fairly significant. This style of fan can move a good bit of air, but it is not designed to do so against a pressure differential.

So my guess is... maybe. It depends on the type of exhaust fan, its quality, whether you are using a carbon filter and, if so, how restrictive it is. If you find that you're seeing higher lights-on temperatures than optimum for your plants (which will, IIRC, be a little lower than recommended until you get your light level up to a decent amount), you could use your other fan for a second exhaust fan. <SHRUGS> Or sell the pair of them to someone and get one high quality exhaust fan that is a centrifugal type and rated to flow in the upper 300 to mid 400 CFM range on high, and run it at less than maximum speed (which will cause it to produce less noise); most people rely on passive intake vents. If you were running HID lighting in air-cooled reflectors, I'd tell you to set them up on their own separate ventilation run with one of those fans, and drawing air from outside of the grow space. And to use the other fan for general grow space air exchange and (if applicable) odor control. Which would be "job done." But that's impossible with LED products like that without some work and hardware hacking. Probably be both easier and cheaper to simply move their power supplies (aka "drivers") outside of the grow space; you'd basically only need some longer wires for that, and then the heat they produce is no longer being dumped directly into the same space that your plants are in.

 

[KnottyDread]

MAN I APPRECIATE THE INFO....so i didnt knw i was short on lights. I wasnt planning on filling the room up just quite....maybe like one 5gal under each light or maybe 2 3gal per light. But ill see about more lighting if you are saying im gonna be short on light. I planned to use regular plants from seed or clone havent really decided yet.

 

[013]

Hey Knotty,

Welcome to forums at 420 Magazine. Nice looking setup! You should check out our sponsors. I got some really nice SP-250‘s LED’s from Mars Hydro. Their rep @SmokeSara is here all the time. They pay to keep 420 going...... so yeah we advocate supporting them, plus there are other excellent lighting vendors to choose from. Mars even gives discounts to members.... that’s hard to beat

 

[InTheShed]

Hey KD! Can't find you anymore. Reach out here or on the gram if you have a spot in your tent.