Cooling/ventilation issue!

Hi everyone,

I have a 4x4x8 grow tent Im using a mars hydro 600 watts(260watts actual power)
And my temps range from 28c to 30c currently using a 4inch exhaust fan(vivosun 202cfm with speed controller turned down)
I have a duct opening at the bottom as a passive intake so the exhaust is also acting as an intake with the negative pressure.
With that being said Im going to upgrade and switch to 600 watts hps in a yield master sun system 6 inch hood I know I will have to upgrade my fan to a 6 inch and I have the option with using a 440 cfm metal fan with S-C or a plastic 390cfm also with a speed controller my issue is that idk which fan to go with to cool the 600watts hps (keeping noise down is important which made me lean more towards the plastic fan but worried it wont be enough to cool it and I will also be adding a filter and dont know if I should pull from inside with the exhaust to hood to filter all inside or the exhaust to hood to filter sitting outside to grab cooler air but the problem would be not exhausting the humid and co2 from the plants and just exhaust the heat from lamp and not the hot air and co2 that rises and also will I need a booster duct fan at the bottom to bring fresh air in please help im confused its my first grow!!

Your existing fan is powerful enough to exhaust a 600W HPS, you don't need a new one. Just get a 6'' to 4'' reducer. No need for a booster fan for air intake, negative air pressure will take care of that.

I think the issue is the ambient temperature of where your grow room is situated.

As far as how to run it.. Put your carbon filter on the floor, attach the fan directly to it. Attach one end of the duct to the hood and the other to the fan. I know a lot of people like putting their carbon filters inside their tent, but I've always ran mine outside the tent with no problems.

smokebros said:

Your existing fan is powerful enough to exhaust a 600W HPS, you don't need a new one. Just get a 6'' to 4'' reducer. No need for a booster fan for passive air intake, negative air pressure will take care of that.

I think the issue is the ambient temperature of where your grow room is situated.

As far as how to run it.. Put your carbon filter on the floor, attach the fan directly to it. Attach one end of the duct to the hood and the other to the fan. I know a lot of people like putting their carbon filters inside their tent, but I've always ran mine outside the tent with no problems.

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Thanks for your reply! And Yes you are right its the ambient temperature where the tent is at its like a little hallway between the restroom and the bedroom(Air conditioned) as soon I turn the Ac on the temps drop in the tent but I cant be having the Ac on it (electric bills&cold temps in bedroom) wanted to pierce hole for ducting leading to the air conditionned bedroom but that would make me hear the fan noise through the duct So im stuck with this issue... also do you confirm I can use the reducer to hook my 4inch 202 cfm fan to the 6 inch hood and 6 inch carbon filter and it will still be enough so need to upgrade??

Akbk31 said:

also do you confirm I can use the reducer to hook my 4inch 202 cfm fan to the 6 inch hood and 6 inch carbon filter and it will still be enough so need to upgrade??

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I assumed you had the carbon filter already for the 4'' fan...

This is what you'd need...

https://www.amazon.com/VIVOSUN-Australia-Charcoal-Pre-filter-Reversible/dp/B01DXYMBU6

https://www.amazon.com/VenTech-VT-DUCT-6-Aluminum-Ventilation/dp/B00DCES1TI

https://www.homedepot.com/p/6-in-to-4-in-Round-Reducer-or-Increaser-R6X4/100111736

smokebros said:

I assumed you had the carbon filter already for the 4'' fan...

This is what you'd need...

https://www.amazon.com/VIVOSUN-Australia-Charcoal-Pre-filter-Reversible/dp/B01DXYMBU6

https://www.amazon.com/VenTech-VT-DUCT-6-Aluminum-Ventilation/dp/B00DCES1TI

https://www.homedepot.com/p/6-in-to-4-in-Round-Reducer-or-Increaser-R6X4/100111736

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So youre saying its okay to buy a 4inch filter use a reducer to hook it to the 6inch hood then another reducer to 4 inch exhaust 202 cfm and it will keep temps down?

smokebros said:

I assumed you had the carbon filter already for the 4'' fan...

This is what you'd need...

https://www.amazon.com/VIVOSUN-Australia-Charcoal-Pre-filter-Reversible/dp/B01DXYMBU6

https://www.amazon.com/VenTech-VT-DUCT-6-Aluminum-Ventilation/dp/B00DCES1TI

https://www.homedepot.com/p/6-in-to-4-in-Round-Reducer-or-Increaser-R6X4/100111736

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So 4inch filter to increaser to 6inch hood then reducer 4inch duct to 4inch inline?

I'm saying that the 4'' inline duct fan that you already have has enough CFM/power to exhaust the 4x4 tent you're talking about. I didn't know that you only have the inline duct fan and not the carbon filter that goes with it...

For simplicity sakes, just buy the 6'' fan, carbon filter, and light + hood and call it good.

smokebros said:

I'm saying that the 4'' inline duct fan that you already have has enough CFM/power to exhaust the 4x4 tent you're talking about. I didn't know that you only have the inline duct fan and not the carbon filter that goes with it...

For simplicity sakes, just buy the 6'' fan, carbon filter, and light + hood and call it good.

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But to save money I can also do what I just mentionned right? Which is carbon filter4inch then increaser 4inch to 6inch to the hood then reducer 6inch to 4inch to the 4inch inline fan?

Akbk31 said:

But to save money I can also do what I just mentionned right? Which is carbon filter4inch then increaser 4inch to 6inch to the hood then reducer 6inch to 4inch to the 4inch inline fan?

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Yes. But you only need one reducer. The 4'' inline duct fan should be able to fit into the carbon filter. In my setup I literally have the fan sitting ontop of the carbon filter.

smokebros said:

Yes. But you only need one reducer. The 4'' inline duct fan should be able to fit into the carbon filter. In my setup I literally have the fan sitting ontop of the carbon filter.

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Doesnt that produce a lot of noise compared to putting them inside the tent?
Also do you out the reducer on top of fan the way you have them set up then duct going inside the tent hooked up to the hood and leave other end of hood open?

smokebros said:

Yes. But you only need one reducer. The 4'' inline duct fan should be able to fit into the carbon filter. In my setup I literally have the fan sitting ontop of the carbon filter.

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Im confused on how to install it the way youre talking about

One end of your light hood will be open. The opposite end of the light hood will have ducting attached to it. That ducting will go out the tent through a hole be attached to your inline fan. The other end of the inline fan will be attached to your carbon filter.

smokebros said:

One end of your light hood will be open. The opposite end of the light hood will have ducting attached to it. That ducting will go out the tent through a hole be attached to your inline fan. The other end of the inline fan will be attached to your carbon filter.

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Got it thank you so much brother!is the fan gonna exhaust or blow tho? And should i open a vent or keep tent sealed! Sorry for throwing too many questions at you I truly appreciate the help!

There's lots of ways to do this. I've always kept my fan/filter outside of the tent because height restrictions. Trying to fit a fan, carbon filter, and light hood in a 4x4 tent is a tough task.

Some people have have a larger/taller grow tent so they can mount their carbon filter inside the tent, but that just hasn't been a really good option for me.

If you're worried about sound then I suggest using insulated ducting. It will cost more money, but it's quieter. If you want a quieter fan then you'll have to shell out more $$, that's why the expensive fans cost so much.

smokebros said:

There's lots of ways to do this. I've always kept my fan/filter outside of the tent because height restrictions. Trying to fit a fan, carbon filter, and light hood in a 4x4 tent is a tough task.

Some people have have a larger/taller grow tent so they can mount their carbon filter inside the tent, but that just hasn't been a really good option for me.

If you're worried about sound then I suggest using insulated ducting. It will cost more money, but it's quieter. If you want a quieter fan then you'll have to shell out more $$, that's why the expensive fans cost so much.

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thank you man! Appreciate the efforts

Akbk31 said:

Got it thank you so much brother!is the fan gonna exhaust or blow tho? And should i open a vent or keep tent sealed! Sorry for throwing too many questions at you I truly appreciate the help!

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I keep the tent sealed. The fan will suck air out of the tent and blow it through the filter.

smokebros said:

I keep the tent sealed. The fan will suck air out of the tent and blow it through the filter.

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What will bring fresh in ? And also thats hot air from the lamp coming out near the tent and being sucked back in isnt that an issue since I already have fairly high ambient temps in that room?

Akbk31 said:

Im confused on how to install it the way youre talking about

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As far as I understand, you won't be able to push any more cfm than your filter can handle. I'd consider getting a 6" filter with close to the same cfm as the fan you're looking at.
You're rigging this to your HPS or LED? My hood has 6" connections, so I matched all my equipment to that.

Edit: I'm in a 2x4x5 tent and even with a 6", I've got very little wiggle room concerning negative pressure. I'd even look into 8" rather than 6" since you're worried about noise. At least with an 8" you can run it at a lower speed, which will be quieter than a 6" at full tilt.

Hashishh said:

As far as I understand, you won't be able to push any more cfm than your filter can handle. I'd consider getting a 6" filter with close to the same cfm as the fan you're looking at.
You're rigging this to your HPS or LED? My hood has 6" connections, so I matched all my equipment to that.

Edit: I'm in a 2x4x5 tent and even with a 6", I've got very little wiggle room concerning negative pressure. I'd even look into 8" rather than 6" since you're worried about noise. At least with an 8" you can run it at a lower speed, which will be quieter than a 6" at full tilt.

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I like your username brother Im from where they make the most of it!

Akbk31 said:

I like your username brother Im from where they make the most of it!

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Haha thank you my friend. I'm a huge fan of the stuff that comes out of Morocco, Nepal, Afghanistan, etc.
I'm fairly new at all this (getting back into it) but feel free to shoot me a pm. I just went through 2 weeks of trying to control the heat in my tent so I may be able to offer some advice.