Intake and Exhaust Help Needed

I built a box that is 4ft x 4ft x 6 1/2ft, I am planning on 9 plants with a 1000 watt HPS, with co2 and a carbon scrubber. fur my intake i want to use 6in inline duct fans i just dont know how many i would need i read that if your running co2 you dont need alot of air intake and comments and ideas on my setup would help. This box is air tight and very solid .

One 6" fan would be more than enough to ventilate your box. 4'x4'x6.5' gives you a volume of 104 cubic feet. A 6" fan will move about 450 cubic feet/minute so you would be exchanging the entire volume of air every 15 seconds. With this much ventilation you might not need an air cooled hood....If you plan on injecting CO2 you will need to use a timer to shut down the fan while the CO2 is being injected.

My bad...you mentioned the box is air tight, if this is the case get an air cooled hood, push the air through the hood so the hood is pressurized. Most hoods are not completely air tight so you will get leakage from the hood, this is good because no odours will be sucked into the hood and out of your box. And the leakage will also add fresh air to your box. You wouldn't need a filter with this setup.

redi jedi said:

One 6" fan would be more than enough to ventilate your box. 4'x4'x6.5' gives you a volume of 104 cubic feet. A 6" fan will move about 450 cubic feet/minute so you would be exchanging the entire volume of air every 15 seconds. With this much ventilation you might not need an air cooled hood....If you plan on injecting CO2 you will need to use a timer to shut down the fan while the CO2 is being injected.

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I would recommend ensuring the room is sealed and simply cool your room with a dual hose portable AC Unit, therefore retaining/recirculating any precious CO2 injected.

hwy420 said:

I would recommend ensuring the room is sealed and simply cool your room with a dual hose portable AC Unit, therefore retaining/recirculating any precious CO2 injected.

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Good point, but the A/C unit would take up half the floor space in his box...

redi jedi said:

Good point, but the A/C unit would take up half the floor space in his box...

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Yup yup it would. Just 1 6" Fan attached to exhaust would be sufficient to get air circulation in that room. You could easily get by with a 4" fan to simply exhaust the hot air, and remember hot air rises, so it's best to exhaust the hot air from the top of the box. Good luck to you good sire

I got a 53"x53"x6' box running a single 600w in a xxl air tight hood with 8" duct openings.I use an 8" duct booster to push air through the hood.Intake & exhaust outside the box,no co2,no filter.If you use co2 you don't want to exhaust from the gro-space.Redi is right on keeping the hood pressurized,any leaks on the hood end up inside the box not outside.My hood runs so cool with this combo you can put your bare hand anywhere on it.Air movment inside the box is a must & VERY important for good plant growth.Also co2 will collect at the bottom of the box if you don't keep it moving.Since I don't use co2 I have a 6" duct booster on a timer,it comes on six times a day for 30 min. to bring fresh air into the box.I use a passive exhaust because where I live I don't have to worry about smell.

Thanks alot to all, one question can i have a fan blowing right on my light instead of exhausting more air and having another hole in my box. and let me get this right if i use my carbon scrubber and a 4in intake fan with running co2 should be sufficient? thanks again guys

A fan just blowing at a 1kw light isn't going to cut it in that small a space....You will need an air cooled hood!!. If your box is air tight, you won't need a carbon filter because your not removing air from the box.Your not going to add air either because you will be injecting CO2. You only need a fan to cool the bulb, no intake fan, no exhaust fan. Like I said before use your fan (if you already have a 6", use it, but a 4" will do fine) to push air through the hood, DO NOT PULL!! or you could have odours outside your box. Hope I've explained it clearly this time...but if not, I'll keep at it until you understand...

Fuck..forgot to say...you'll need a small oscillating fan to stir up the CO2, someone already mentioned this, since carbon dioxide is heavier than air it will pool at the bottom of your box.

I am running 2 4 inch 80 cfm fans in a fridge and they are more than enough

TCurtiss said:

I am running 2 4 inch 80 cfm fans in a fridge and they are more than enough

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Are you running a 1000 W hps in that fridge too?