95 degrees too hot? Why isn't my ventilation working better?

Here is my setup:

Dark Room DR150 II 60x60x80 Tent.

S&P TD-200 8" Round Duct Fan 538/476 cfm.

CanLite Filter 600cfm.

Sun System Cool Sun HID Reflector Air Cooled Hood.

Lumatek 1000w Ballast.

1000w Agrosun Super Red Sodium Bulb.

I have everything tied together with 6" insulated duct and the fan set to "high" setting, 534cfm. I have both passive intakes open with 2 fans blowing air at one of the passive intakes. The other passive intake unfortunately backs up to a wall for the most part. I also have an oscillating fan on the inside of the tent. This is how I have the exhaust setup:

Carbon Filter > Insulated Ducting > Air Cooled Hood > Insulated Ducting > Inline Fan > Insulated Ducting going about 4 ft out of the tent up by the air conditioners hot air return for the room.

During the day I can see temps of 95 degrees F in the tent even though ambient in the room is only 75.7 F. The room the tent is in feels nice and cool with good air flow. How come my ventilation is not getting the job done? Is 95 deg ok to grow in?

Well just from what you said it could be the second passive intake being blocked. I know when I built my own cab I was surprised by how much opening was needed to properly let enough air in for my exhaust. I had 95 temps and added a whole other exhaust fan to remedy but didn't help much. Only once I started cuting out 2 square foot holes did I see any improvement. You want negative pressure but not much. So try and get the second intake wide open if possible. If not I've done complete grows in 95 with a scarce preemy seed or two in each plant. Its not ideal but the plants will adjust to the temps. How do you think bud grows in Brazil or Jamaica... or the southern states in the summer for that matter.

95 is too hot. your fan would be sufficient for cooling your light IF you didn't have your carbon filter capping it off. bypass the tent with the light and get another fan to hook up to your carbon filter. the filter is reducing your airflow by over half i would guess. also are you running your lights during the daytime? try running them at night from 8 to 8. it can be convienent to tie your light exhaust into your hot air return and your air conditioner will dissapate the heat through the house, and then tie your carbon filter outside to remove the heat and humidity from the room.

bostoner said:

Well just from what you said it could be the second passive intake being blocked. I know when I built my own cab I was surprised by how much opening was needed to properly let enough air in for my exhaust. I had 95 temps and added a whole other exhaust fan to remedy but didn't help much. Only once I started cuting out 2 square foot holes did I see any improvement. You want negative pressure but not much. So try and get the second intake wide open if possible. If not I've done complete grows in 95 with a scarce preemy seed or two in each plant. Its not ideal but the plants will adjust to the temps. How do you think bud grows in Brazil or Jamaica... or the southern states in the summer for that matter.

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The tent is in a corner so if I turn it I will just block off the other vent. I could try opening the door or window of the tent a little to allow a little more air in though. What do you think about that? Is there a way I can test if I even have negative pressure in the tent?

Stealthbomb said:

95 is too hot. your fan would be sufficient for cooling your light IF you didn't have your carbon filter capping it off. bypass the tent with the light and get another fan to hook up to your carbon filter. the filter is reducing your airflow by over half i would guess. also are you running your lights during the daytime? try running them at night from 8 to 8. it can be convienent to tie your light exhaust into your hot air return and your air conditioner will dissapate the heat through the house, and then tie your carbon filter outside to remove the heat and humidity from the room.

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I didn't really want to add another fan because this is already way more noise than I would've liked. That and I don't have another $180 for a fan..

I open the doors of my tent all the time when the light is on to lower temps and give them more fresh air.

Let em breathe. I got a Dr120 and always leave a whole side open when lights are on. Cool fresh air for the ladies!

Medical420MI said:

I open the doors of my tent all the time when the light is on to lower temps and give them more fresh air.

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colerbear said:

Let em breathe. I got a Dr120 and always leave a whole side open when lights are on. Cool fresh air for the ladies!

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Will this allow smelly air to escape without going through the filter though? Do you guys use carbon filters with your setups? If I can still keep smell under control with the door open I know I can get temps down a lot! That would be great news!

By the way, I am doing this testing during the day. Once I actually have ladies going I will be running at night.

highasfvck said:

Will this allow smelly air to escape without going through the filter though? Do you guys use carbon filters with your setups? If I can still keep smell under control with the door open I know I can get temps down a lot! That would be great news!

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Yes it will definitely not control your odors. Trust me, my DR150 is sealed (back draft dampers and all) with a carbon filter/fan scrubbing the air 24/7 and when the exhaust/intake fans kicks on it still smells a little. I plan on getting a second carbon filter for my exhaust fan. I am running 4 inline fans total. 1 for intake, 1 for exhaust, 1 for scrubbing odors, and 1 on 1000 watt lamp exhausting that straight to the outside of the tent. I keep my daytime temps around 87 degrees but that is because I have CO2 and it helps them, otherwise I would be having problems with heat stress.

Good luck and keep it green.

highasfvck said:

By the way, I am doing this testing during the day. Once I actually have ladies going I will be running at night.

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Just a word of caution, beware of changing the photo period too much at once. It can stress them out just as much as heat. If you are running 24/0 and just switch to 12/12 at night that's fine but if you switch from 8am-8pm to 9pm-9am, that could be very stressful for your girls.

I'm suspect of the fan you mentioned. Is it an inline fan or is it a duct booster fan. My vortex 8" is in the 750 cfm neighborhood. If it's a ductfan, it won't have the cfms to pull through that filter it's full rating. It could be reduced by a high % .

^^^^great info guys..........and yes your best bet while keeping odors down is to buy another inline/not what you wanted to hear sorry.....but your cfms ARE cut in half by all the restrictions in you ducting......get a small 250cfm inline(less than $100/ low db) and run it with the scrubber while the big boy handles the lights(have you considered dimming it/75%-50%/i know reduced yield, but no jail)......their aren't many options here if you want to keep it undetectable to the nose........be safe/happy growing

What do ya mean " Insulated Ducting going about 4 ft out of the tent up by the air conditioners hot air return for the room." Is your exhaust line hooked into your a/c exhaust? You may be causing a backflow problem if this is the case. Everytime your a/c kicks in there is too much flow and your inline cannot hold back the flow of hot exhaust from the a/c.

Ive had this happen and moved my a/c unit to another exhaust and my problem was solved. A seperate filter in the main room is also a good idea.

budleydoright said:

I'm suspect of the fan you mentioned. Is it an inline fan or is it a duct booster fan. My vortex 8" is in the 750 cfm neighborhood. If it's a ductfan, it won't have the cfms to pull through that filter it's full rating. It could be reduced by a high % .

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It's an inline fan, from what I understand was supposed to be the most quiet, but it's really not quiet enough for me as it is...

Sir.Ganga said:

What do ya mean " Insulated Ducting going about 4 ft out of the tent up by the air conditioners hot air return for the room." Is your exhaust line hooked into your a/c exhaust? You may be causing a backflow problem if this is the case. Everytime your a/c kicks in there is too much flow and your inline cannot hold back the flow of hot exhaust from the a/c.

Ive had this happen and moved my a/c unit to another exhaust and my problem was solved. A seperate filter in the main room is also a good idea.

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It's not where the A/C blows air into the room, it's where it sucks out the old air and recirculates it. It's not completely hooked into it, just exhausting near it. This is a central A/C system, not a portable unit.

berkman858 said:

Yes it will definitely not control your odors. Trust me, my DR150 is sealed (back draft dampers and all) with a carbon filter/fan scrubbing the air 24/7 and when the exhaust/intake fans kicks on it still smells a little. I plan on getting a second carbon filter for my exhaust fan. I am running 4 inline fans total. 1 for intake, 1 for exhaust, 1 for scrubbing odors, and 1 on 1000 watt lamp exhausting that straight to the outside of the tent. I keep my daytime temps around 87 degrees but that is because I have CO2 and it helps them, otherwise I would be having problems with heat stress.

Good luck and keep it green.

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Ughhh this sucks... I may need to throw a 600w back in... I was hoping to improve yields over my last setup.

berkman858 said:

Just a word of caution, beware of changing the photo period too much at once. It can stress them out just as much as heat. If you are running 24/0 and just switch to 12/12 at night that's fine but if you switch from 8am-8pm to 9pm-9am, that could be very stressful for your girls.

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Theres no ladies in there now. I am doing some dry run testing of the new setup.

I don;t think yout fan has the pressure to pull through that filter and still deliver the desired cfm. You need a stronger louder fan at min.

budleydoright said:

I don;t think yout fan has the pressure to pull through that filter and still deliver the desired cfm. You need a stronger louder fan at min.

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Stronger AND louder? I understand the former but the latter??

Bigger is generally louder is what he is saying.

Plants can take alot of heat.
My shed cab will get to 110' for a few months of the summer, same temp as the outdoor..
I seen green houses get to 120' an the plants were thriving.
Its not optimum, but they have evolved to handle the heat....

berkman858 said:

Stronger AND louder? I understand the former but the latter??

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I'm guessing you chose this fan because it's quiet. Most 8" inline fans put out 50% more cfm. Prob be better off with a bigger fan and insulate it to quiet it down.

SCARHOLE said:

Plants can take alot of heat.
My shed cab will get to 110' for a few months of the summer, same temp as the outdoor..
I seen green houses get to 120' an the plants were thriving.
Its not optimum, but they have evolved to handle the heat....

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So true! i think we get hyperfocused on providing optimum conditions at any cost. If you just use what you have, play the cards your dealt and do the best you can. You will have something nice to put in your bag at the end. It might not be as dense or as much but the rewards are still there for those willing to make it happen for themselves.