Please help need it

I completed a grow in my passive setup.


I have a 8*12 room with a veg tent 4*4 and 5x5 flower. The tents are passive venting out to a small vented attic with a 10” scrubber just incase. Both tents have 6” carbon filters. I have temp issues, even fan all the way on I think I hit 90-91 in heat of summer.

These two tents contain flood tables. I want to get a mini ac with humidifer and carbon filter place it in room and vent to attic. I saw prices around 500-600.
I would keep the carbon filters in the tents venting but to the room outside the tent. Outside the tent I would have a fan and carbon filter. Install y splitter run the air to both tents.

Any thoughts on this? Someone mentioned split ac I def can’t put that on the side of my house. Is it worth it to break from passive.

There seems to be a big misconception hovering these forums with people who speak to intake and exhaust fans as if their supposed to help cool your grow space.

I'm not saying you think that, but it sounds like it when you said break from passive. If the temps in that room are hot, your tents will be hot with or without fans.

You running 3 fans with filters is excessive for 2 tents. All you're doing is running your fans harder and less effectively.

All that humid air and exhausted heat to your attic although vented, WILL absolutely be the perfect cocktail to grow some beastly mold/bacteria.

You don't need to run the AC to the tents with hoses and/or splitters. Control the room environment that the tents pull air from and that will help.

My Name is Mike said:

There seems to be a big misconception hovering these forums with people who speak to intake and exhaust fans as if their supposed to help cool your grow space.

I'm not saying you think that, but it sounds like it when you said break from passive. If the temps in that room are hot, your tents will be hot with or without fans.

You running 3 fans with filters is excessive for 2 tents. All you're doing is running your fans harder and less effectively.

All that humid air and exhausted heat to your attic although vented, WILL absolutely be the perfect cocktail to grow some beastly mold/bacteria.

You don't need to run the AC to the tents with hoses and/or splitters. Control the room environment that the tents pull air from and that will help.

Click to expand...

Good suggestion. I’ll take it.

My Name is Mike said:

There seems to be a big misconception hovering these forums with people who speak to intake and exhaust fans as if their supposed to help cool your grow space.

Click to expand...

They do cool grow spaces providing the air coming in is not already warmer than you want it.
Its literally the most common method of managing heat in a grow space world wide.

coreywebster said:

They do cool grow spaces providing the air coming in is not already warmer than you want it.
Its literally the most common method of managing heat in a grow space world wide.

Click to expand...

On my situation here. With my fans on high. I noticed that my humidity reading max outside 97%, however where I am venting to my attic max is 59-61. Is it worth it for me to add another vent. Seems like I am property vented. Again. I took humidity readings every hour for past 4 months.

coreywebster said:

They do cool grow spaces providing the air coming in is not already warmer than you want it.
Its literally the most common method of managing heat in a grow space world wide.

Click to expand...

Dude you're partially wrong.. It exchanges air, it doesn't cool it. You added the most important bit to why it would be effective and that's "providing the air coming in is not already warmer".

There's nothing built into a standard inline that has cooling ability. It does 1 job and 1 job only and thats exchange airflow.

Based on the info OP shared, he's exchanging from a room that appears to be not cooled (assuming warm) with tent air that's very warm which will never cool down in that situation with 1, 2, 50 fans unless his environment is controlled which is what I shared.

My Name is Mike said:

Dude you're partially wrong.. It exchanges air, it doesn't cool it. You added the most important bit to why it would be effective and that's "providing the air coming in is not already warmer".

There's nothing built into a standard inline that has cooling ability. It does 1 job and 1 job only and thats exchange airflow.

Based on the info OP shared, he's exchanging from a room that appears to be not cooled (assuming warm) with tent air that's very warm which will never cool down in that situation with 1, 2, 50 fans unless his environment is controlled which is what I shared.

Click to expand...

no it’s a closet with a vent in a home with two ac units. The home is cooled to 77 on the floor with tent. I was flowering in both tents at night so 680watt and roughly 1100watt on the other. It’s a small space i plan to run reg and flower now so it will be less.

I noticed my peak humidity at 61. I plan on keep
Monitoring and have my 10” scrubber in small attic run to outside.

The whole house is on ac 2 ac units two floor it’s pulling from 77 degree cooled. I had two tents both in flowery 1100 and 680. I’m moving to dedicated flower and veg tent so the heat will be a little less.

on the small attic I’m thinking I’ll vent the scrubber to outside, I don’t want to vent to outside without the fail safe.

Ladiesonly said:

no it’s a closet with a vent in a home with two ac units. The home is cooled to 77 on the floor with tent. I was flowering in both tents at night so 680watt and roughly 1100watt on the other. It’s a small space i plan to run reg and flower now so it will be less.

I noticed my peak humidity at 61. I plan on keep
Monitoring and have my 10” scrubber in small attic run to outside.

The whole house is on ac 2 ac units two floor it’s pulling from 77 degree cooled. I had two tents both in flowery 1100 and 680. I’m moving to dedicated flower and veg tent so the heat will be a little less.

on the small attic I’m thinking I’ll vent the scrubber to outside, I don’t want to vent to outside without the fail safe.

Click to expand...

So your closet is 8'x12'? I thought you were growing in a room.

Nonetheless, to wrap my head around this. The floor is cooled to 77 degree. Is this the temperature of the room/closet that have the tents?

Currently, you are venting to an attic. Air is being pulled from the room that's on a floor kept at 77 degree temp and the tents are rising to 91 running fans at capacity. Either something doesn't make sense or I have it wrong.

Yes it’s a closet of a 2nd master in a fucked up house. I know it’s tight, the upstairs ac runs between 76 and 77 there is ample air that is consisten in temperature it actually has a small return. I and thinking of adding a ac infinity register fan to it for drawing more air.

I would say if anything there a little smaller. I’m running 1100watt light and 680watt light. It’s in the 90s outside temp.

Ladiesonly said:

I have a 8*12 room with a veg tent 4*4 and 5x5 flower. The tents are passive venting out to a small vented attic with a 10” scrubber just incase. Both tents have 6” carbon filters. I have temp issues, even fan all the way on I think I hit 90-91 in heat of summer.

Click to expand...

Usually its a good idea to vent actively out of the room in order to prevent that the tents intake air gets mixed together with the old air (which is already hot n humid...)

Kassiopeija said:

Usually its a good idea to vent actively out of the room in order to prevent that the tents intake air gets mixed together with the old air (which is already hot n humid...)

Click to expand...

Yeah I am venting to a mini attic. Other side of wall.

I ask a lot of questions because I'm a visual person, but I'm hoping to help. Each tent, whats the size of your passive intake hole? I can't seem to understand why your temps would be spiking so high with a consistent room temp and exhaust outside of room.

Conclusions so far are:

Passive intakes are not big enough to exchange the air

Fans may be too underpowered

Room temp isn't consistent and increases with hot days

77 degree starting point is going to require more than a couple of 6" fans to exchange the air at a fast enough rate to keep it less degrees above ambient with 800+ and 1000+ watts in those tents.

Im assuming he has 6" fans attached to his 6" filters , sounds like that then a bigger fan and filter in the attic venting that.

Take the 5x5 tent as an example, 1100w (led or hps?)

HPS say 78 degrees target temp = 3476cfm
say 80 degrees target temp = 1158cfm

LED say 83 degrees target temp = 579cfm
say 85 degrees target temp= 496cfm

That's not taking into account loses from filters. Probably wants an extra 30% on top for losses.

Floor needs to be running considerably cooler than 77 to getaway with simple extraction.

If using LED then those cfm ratings are achievable , but if using hps then its not really practical to run 3476cfm.

Really I think a picture paints a thousand words.
Or at least a lot more detail of all parts involved because no mention of what fans are running on those 6" filters.

coreywebster said:

77 degree starting point is going to require more than a couple of 6" fans to exchange the air at a fast enough rate to keep it less degrees above ambient with 800+ and 1000+ watts in those tents.

Im assuming he has 6" fans attached to his 6" filters , sounds like that then a bigger fan and filter in the attic venting that. They are 6" inch fans

Take the 5x5 tent as an example, 1100w (led or hps?) This is LED

HPS say 78 degrees target temp = 3476cfm
say 80 degrees target temp = 1158cfm

LED say 83 degrees target temp = 579cfm These look spot on.
say 85 degrees target temp= 496cfm These look spot on

That's not taking into account loses from filters. Probably wants an extra 30% on top for losses.

Floor needs to be running considerably cooler than 77 to getaway with simple extraction.

If using LED then those cfm ratings are achievable , but if using hps then its not really practical to run 3476cfm.

Click to expand...

The one thing I am switching is keeping the 4x4 for Veg only at 300watt. Am I better off with AC. I will reply with a diagram. Thanks for help. I also can switch 6" in 5x5 to 8" fan. I purchased it already.

Here is the treasure map.

Clarifying question. The 2 vents, vent 1 in veg tent and vent 2 in flower tent leading to attic. The fan/filter combo is hooked to that duct right? Or is the fan/filter hanging or placed on floor without connecting to the duct vent?

Also no mention of passive intake in diagram. How big is the intake hole?

Yes the fan filter goes through a duct to the attic. In both tents , two separate holes in wall.

77f starting temp isn't leaving much room for your lighting and residual heat from other units. If that is as low as starting temp can get and you cant add individual ac to the lung room it only really gives two options.

If you are using hps you could swap out to cheap open wing cmh and/or led to lower your W usage while not losing too much light intensity.
I guess it wouldn't be much more expensive than the extra AC cost +W over time you would require otherwise. If you are already using leds but can't get AC then you will have to lower the led W to a where your temps are in range.

If you are already using leds you could have looked at the VPD charts but you would have to increase humidity a lot, even if you could achieve that in a constant flow setting it wouldn't be very good for your attic. Is venting to the attic a fixed part of the plan?.

The passive air is from the bedroom?.