Ventilation issues

[Lulic86]

So I have a room that is 9ftx3.5ftx6ft , from calculations I've seen you multiple these together and then multiple that answer by 1.2 (20% for carbon slumber loss) which gives me 226cfm, I have a 300 cfm 6" fan, my filter and fan are mounted to ceiling above light together then a 6" duct runs thru my cool tube and exhausts outside, I have 100cfm 4" boster fan feeding my room with air from inside my house , my problem is heat or humidity , either I turn the fan up and I can get temperatures about 71 which is good from.what I heard , 68-80F is acceptable, but when I turn up my fan all my humirty drops from 65ish to 35 ish within minutes , so I tried playing with my fan control to find a sweet spot and I just cant figure it out , either the humidity is good and temp high or temp good and humidity too low , I also have 5 fans circulating air constantly , theres not 1 dead spot in the grow room that you cant feel a breeze, I even amid one direct at tube blowing towards the filter and no difference, I also have a 2 duct ac system so I tried turning that on so cool the air but again second i do my humidity drops instantly....please help , my only other thing I can think of is to use a fan directly for cool tube sucking air from.outside and blowing it back outside and run fan on full and have seperate fan and filter on low for smell, has anyone every had this issue?? Please help , I have so much time and money invested I'm this room

 

[Hrenklin]

You cannsupliment with a humidifyer

 

[TurboBucket]

What are the temp and rh of your incoming air? I'm assuming cold and dry based on your description.

71° is honestly on the low side. Plant metabolism increases with temperature. With LEDs your aiming for 75-80°.

If the air in your home is really dry you should run a humidifier in there anyways to help with your own indoor health/comfort levels. By increasing the rh of the air being drawn into the tent you'll also increase the humidity inside.

When you run the AC it removes humidity, that's what the water is that drains out of them, the condensation from the air passing across the cold evaporator coil.

 

[Lulic86]

You cannsupliment with a humidifyer

I have 2 of them in the room already
..sorry forgot to say that

 

[Lulic86]

What are the temp and rh of your incoming air? I'm assuming cold and dry based on your description.

71° is honestly on the low side. Plant metabolism increases with temperature. With LEDs your aiming for 75-80°.

If the air in your home is really dry you should run a humidifier in there anyways to help with your own indoor health/comfort levels. By increasing the rh of the air being drawn into the tent you'll also increase the humidity inside.

When you run the AC it removes humidity, that's what the water is that drains out of them, the condensation from the air passing across the cold evaporator coil.

Thays great information actally , the room its sucking from is right beside my furnace at about waist height , I'll put a meter in my house and check the RH and maybe instead put another humidifier in the room it sucks from....

 

[JKB1989]

I have the same problem in my grow area. I'm just now getting ready to put an portable ac unit in the grow room. My thoughts are that with the ac unit keeping the temps around 80 degrees I will be able to slow down the exhaust fan. I think that is the whole problem. The exhaust fan is constantly drawing in dry air from the room. Being able to slow exhaust also slows the amount of dry air coming in. Allowing the humidifier to actually work as it's supposed to. Between the plants themselves the humidifier and the heat from the lights I'm hoping to solve this problem. Only time will tell.

 

[TurboBucket]

I have the same problem in my grow area. I'm just now getting ready to put an portable ac unit in the grow room. My thoughts are that with the ac unit keeping the temps around 80 degrees I will be able to slow down the exhaust fan. I think that is the whole problem. The exhaust fan is constantly drawing in dry air from the room. Being able to slow exhaust also slows the amount of dry air coming in. Allowing the humidifier to actually work as it's supposed to. Between the plants themselves the humidifier and the heat from the lights I'm hoping to solve this problem. Only time will tell.

Depending on if you get a single or dual hose portable AC the AC is also going to vent your grow air outside.

Single hose pulls from inside the space to cool the condenser. Which contributes to more exhaust.
Dual hose uses outside air. So it doesn't affect your tent air.

 

[multiVortex]

Slow that fan down enough to get the daytime temps up around 78F-80F.

Slowing down the exhaust will pull less out, which then will better allow your humidifier to keep the RH up. Your temps overnight should be 68F-70F, and never below 63F as a general guideline. (That's about the point where the plants metabolism will slow down and can cost you harvest weight.)

Check out some of the VPD charts as well, and find the range for your RH based on the temp and life stage of your plants. (I'm assuming veg as you're wanting higher RH.)

Maybe also look at upgrading to LED's. Our sponsor Budget LED has excellent quantum board style lights that would rock that space you're in.

 

[Lulic86]

Slow that fan down enough to get the daytime temps up around 78F-80F.

Slowing down the exhaust will pull less out, which then will better allow your humidifier to keep the RH up. Your temps overnight should be 68F-70F, and never below 63F as a general guideline. (That's about the point where the plants metabolism will slow down and can cost you harvest weight.)

Check out some of the VPD charts as well, and find the range for your RH based on the temp and life stage of your plants. (I'm assuming veg as you're wanting higher RH.)

Maybe also look at upgrading to LED's. Our sponsor Budget LED has excellent quantum board style lights that would rock that space you're in.

That's my issue , when I slow fan down to get the correct humidity my heat rises up for 84-85....I have a dual duct ac unit but even with both ducts run outside the area , my humidity drops still....currently I'm looking into have a 6" fan just for my light seperate from room ventaliation , that way I can run that fan on high, then I will install the filter and another 6" fan just for my ventilation in room and can run that at whatever speed to control my humidity....I def want led but it's just not in budget right now

 

[Lulic86]

Depending on if you get a single or dual hose portable AC the AC is also going to vent your grow air outside.

Single hose pulls from inside the space to cool the condenser. Which contributes to more exhaust.
Dual hose uses outside air. So it doesn't affect your tent air.

I do have a dual hose but it still seem to draw out my humidity for some reasons..

 

[Lulic86]

I have the same problem in my grow area. I'm just now getting ready to put an portable ac unit in the grow room. My thoughts are that with the ac unit keeping the temps around 80 degrees I will be able to slow down the exhaust fan. I think that is the whole problem. The exhaust fan is constantly drawing in dry air from the room. Being able to slow exhaust also slows the amount of dry air coming in. Allowing the humidifier to actually work as it's supposed to. Between the plants themselves the humidifier and the heat from the lights I'm hoping to solve this problem. Only time will tell.

Let me know because I have a dual duct ac and it still seems to drop my humidity...

 

[Southerncough]

How high does your temp go with then fan turned down?
Also, what strains are you growing?
I struggle to stay below 80 with LEDs, exhaust fan and an ac blowing but some strains dont mind it. Sure, when i ran hindu kush it was a mess of larf because she wanted a cool room. But my hybrid strains are happy.

 

[TurboBucket]

Again. AC removes humidity from the air. You need something more like an evaporative/swamp cooler, they add humidity while cooling. Most popular in the arid Southwest states.

 

[Southerncough]

Again. AC removes humidity from the air. You need something more like an evaporative/swamp cooler, they add humidity while cooling. Most popular in the arid Southwest states.

Ooh, that would be a perfect solution! I've seen lots of videos of people building them with box fans and fountain pumps running water through some kind of honeycomb mesh. There's an orchid greenhouse near my work that has one that takes up a whole wall where hot outside air is pulled through the "waterfall" then across the room and out through large fans on the other side of the greenhouse.

 

[multiVortex]

That's my issue , when I slow fan down to get the correct humidity my heat rises up for 84-85....I have a dual duct ac unit but even with both ducts run outside the area , my humidity drops still....currently I'm looking into have a 6" fan just for my light seperate from room ventaliation , that way I can run that fan on high, then I will install the filter and another 6" fan just for my ventilation in room and can run that at whatever speed to control my humidity....I def want led but it's just not in budget right now

How many speeds are on your fan? Mine has 8 different settings. In veg, I run it slower to keep humidity up, flower I run it faster to keep it down.

If there is middle ground to go just a little slower than you had it where it was 84, then maybe humidity is close enough?

 

[Lulic86]

How high does your temp go with then fan turned down?
Also, what strains are you growing?
I struggle to stay below 80 with LEDs, exhaust fan and an ac blowing but some strains dont mind it. Sure, when i ran hindu kush it was a mess of larf because she wanted a cool room. But my hybrid strains are happy.

Currently I dont have any plants in room as I'm in testing phase....I wanted to make sure the room was functioning properly before using my babies as tests , that is true, green crack strain can go up to 90 degrees even I read but most strains I've read are between 65-80F , I dont want to be limited in only growing those strains as I put alot of time and money into the project.....

 

[TurboBucket]

Ooh, that would be a perfect solution! I've seen lots of videos of people building them with box fans and fountain pumps running water through some kind of honeycomb mesh. There's an orchid greenhouse near my work that has one that takes up a whole wall where hot outside air is pulled through the "waterfall" then across the room and out through large fans on the other side of the greenhouse.

That would be cool to see. Evap coolers have the advantage of being wonderful pieces of functional art. There's a city in India that uses them to cool the town square.

Folks have been using water filled clay pots to cool their living quarters throughout history. It's simple and effective, just the way I like it. They obviously don't work in every situation/environment but they are very efficient when you can.

It takes 940 BTUs to change a lb of water into steam without changing the temperature. So every lb of water that evaporates removes over 1000btus, one gallon of water weighs roughly 8 pounds so one gallon of water evaporated per hour is equal to the smallest window shaker AC units at 8000btu/hr and it will cost you maybe 1/10th of the electricity, and also be slightly more appealing to hear (most folks enjoy the sound of a waterfall/rushing water compared to a compressor.

Now because your evaporating water into the air your rh is also going to rise. Your adding 3800 grams of water per gallon. At 77°f 50%rh assuming normal atmospheric conditions air contains roughly 4.5 grams of water per lb of air. At 35%rh it only contains about 3 grams of water per lb of air. So you could humidify 2500 lbs of air from 35-50% and remove 8000btus of heat from the room by evaporating 1 gallon of water per hour.

1 cubic foot of dry air weighs roughly .08lbs so that's approximately 200 cubic feet.

 

[Lulic86]

How many speeds are on your fan? Mine has 8 different settings. In veg, I run it slower to keep humidity up, flower I run it faster to keep it down.

If there is middle ground to go just a little slower than you had it where it was 84, then maybe humidity is close enough?

Will 84 work tho? As of right now I bought a new fan and filter from vivosun that I'll use just for exhausting the room , and then I'll have another 6" duct strictly for my cool tube , completely seperate from room ventilation, when I run fan on full for the light , I can easily get it down to 71-72 , then my exhust venting for room I can run very low just for getting fresh air into room and get that slight negative pressure for smell aswell......I'll let you guys know how that works out , I would of just went led but bought the 1000w set up 6 years ago and sat in storage brand new , plus I researched that hps yields more typically , 1 video I watched , a guy had a big tent , half tent led and half hps , the hps side had bigger and fuller plants , both same exact strains , grown same time same everything

 

[Lulic86]

That would be cool to see. Evap coolers have the advantage of being wonderful pieces of functional art. There's a city in India that uses them to cool the town square.

Folks have been using water filled clay pots to cool their living quarters throughout history. It's simple and effective, just the way I like it. They obviously don't work in every situation/environment but they are very efficient when you can.

It takes 940 BTUs to change a lb of water into steam without changing the temperature. So every lb of water that evaporates removes over 1000btus, one gallon of water weighs roughly 8 pounds so one gallon of water evaporated per hour is equal to the smallest window shaker AC units at 8000btu/hr and it will cost you maybe 1/10th of the electricity, and also be slightly more appealing to hear (most folks enjoy the sound of a waterfall/rushing water compared to a compressor.

Now because your evaporating water into the air your rh is also going to rise. Your adding 3800 grams of water per gallon. At 77°f 50%rh assuming normal atmospheric conditions air contains roughly 4.5 grams of water per lb of air. At 35%rh it only contains about 3 grams of water per lb of air. So you could humidify 2500 lbs of air from 35-50% and remove 8000btus of heat from the room by evaporating 1 gallon of water per hour.

1 cubic foot of dry air weighs roughly .08lbs so that's approximately 200 cubic feet.

Wow that's alot of kool information right there , thank you!!!so it's called "evap coolers" ?

 

[Lulic86]

Thank you to everyone for all your replys and helpful information, my first time being part of a forum and I question why I havent joined sooner lol Truely appreciated my friends!!