Ventilation question

[Cabbagelit]

Getting some powdery mildew on my first grow on the lower leaves of my bigger plant. I’m positive it’s an airflow issue. Here’s a few pics of how my fans are setup. To be honest I want to optimize on my air flow. Would love some advice... Also please suggest some good 6 in intake fans I can install to get some fresh air In There

 

[printer]

I do not have a tent so I am just guessing what you have (no mention of what equipment). Looks like you have intake and exhaust ducts but they are closed. How about opening them?

 

[Grow So High]

I recommend the AC infinity cloud line series. It’s quiet and effective. Also recommend getting small fans In there to just move air around. Is that a 4x4?

 

[Cabbagelit]

I recommend the AC infinity cloud line series. It’s quiet and effective. Also recommend getting small fans In there to just move air around. Is that a 4x4?

Yes it’s a 4x4 tent. Going to do that ASAP!! Once I get some Extra money. I got a 4 in vivosun Inline fan and carbon filter.1 fan on the ground blowing hot air out the vents at the bottom of tent. And then got a fan pointing at the carbon filter. Temps are 84 degrees. Keeping my RH at 40-55 in late vegetation stage. Do I need a intake fan blowing in fresh air? Or should I just get one more fan in The tent

 

[Cabbagelit]

I do not have a tent so I am just guessing what you have (no mention of what equipment). Looks like you have intake and exhaust ducts but they are closed. How about opening them?

Do I open the vent doors all the way??

 

[xtsho]

You want to vent the carbon filter from one of the vents at the top of the tent not the bottom. Open the bottom vents for passive air intake. That will pull the air from the bottom and out the top which is what you want and will increase the airflow. Heat rises so your fan on the ground isn't doing much. That 4 inch fan should be fine if you set it up correctly.

 

[Cabbagelit]

You want to vent the carbon filter from one of the vents at the top of the tent not the bottom. Open the bottom vents for passive air intake. That will pull the air from the bottom and out the top which is what you want and will increase the airflow. Heat rises so your fan on the ground isn't doing much. That 4 inch fan should be fine if you set it up correctly.

The 4 inch fan is on the side of my tent pointing upward at the carbon filter. Should I bring it as high as I can pointing straight at it?? Also the carbon filter is up at the top

 

[Cabbagelit]

You want to vent the carbon filter from one of the vents at the top of the tent not the bottom. Open the bottom vents for passive air intake. That will pull the air from the bottom and out the top which is what you want and will increase the airflow. Heat rises so your fan on the ground isn't doing much. That 4 inch fan should be fine if you set it up correctly.

Here’s maybe a better view of what’s going on. I got all 2 vents open at the bottom. I’m thinking I should bring the 4 inch up higher and point it directly at the filter

 

[xtsho]

Pull cool air in from the bottom, exhaust from the top. Here's an illustration of several ways to setup the fan and filter properly.

 

[Grow So High]

Yes it’s a 4x4 tent. Going to do that ASAP!! Once I get some Extra money. I got a 4 in vivosun Inline fan and carbon filter.1 fan on the ground blowing hot air out the vents at the bottom of tent. And then got a fan pointing at the carbon filter. Temps are 84 degrees. Keeping my RH at 40-55 in late vegetation stage. Do I need a intake fan blowing in fresh air? Or should I just get one more fan in The tent

I was in a similar situation in my 4x4 a while ago, I was using a 4” inline fan with a carbon filter and 2 fans inside the tent for airflow. I recommend if you don’t have an exhaust fan to do what’s called a passive exhaust. You open up one one of the vent holes on your tent, opposite of your inline fan. For example if your inline fan is drawing air through the top right then you make a passive exhaust through the bottom left of your tent. If you have ducting use that just be careful for light leaks. If you bend the ducting in a S shape it should avoid that problem. This along with a fan inside should give you good enough airflow. You should be able to see the leaves on your plants move a little from the air. Sorry for rambling lol hopefully this makes sense

 

[Cabbagelit]

Did I help this problem by raising the fan that’s exhausting the air up more? Temps seemed to have gotta a little cooler after doing that

 

[xtsho]

Did I help this problem by raising the fan that’s exhausting the air up more? Temps seemed to have gotta a little cooler after doing that

That's fine the way you have the exhaust fan hooked up. Now make sure you open a vent at the bottom. Like @Grow So High said use a piece of ducting to prevent light from getting into the tent. You also want to filter the air coming into the tent to prevent dust, lint, and other unwanted particulates from getting inside the tent.

 

[Cabbagelit]

You guys are amazing

 

[Cabbagelit]

I was in a similar situation in my 4x4 a while ago, I was using a 4” inline fan with a carbon filter and 2 fans inside the tent for airflow. I recommend if you don’t have an exhaust fan to do what’s called a passive exhaust. You open up one one of the vent holes on your tent, opposite of your inline fan. For example if your inline fan is drawing air through the top right then you make a passive exhaust through the bottom left of your tent. If you have ducting use that just be careful for light leaks. If you bend the ducting in a S shape it should avoid that problem. This along with a fan inside should give you good enough airflow. You should be able to see the leaves on your plants move a little from the air. Sorry for rambling lol hopefully this makes sense

Took some
Time to redo my tent. I hope I got it dialed in now?

 

[Grow So High]

I was in a similar situation in my 4x4 a while ago, I was using a 4” inline fan with a carbon filter and 2 fans inside the tent for airflow. I recommend if you don’t have an exhaust fan to do what’s called a passive exhaust. You open up one one of the vent holes on your tent, opposite of your inline fan. For example if your inline fan is drawing air through the top right then you make a passive exhaust through the bottom left of your tent. If you have ducting use that just be careful for light leaks. If you bend the ducting in a S shape it should avoid that problem. This along with a fan inside should give you good enough airflow. You should be able to see the leaves on your plants move a little from the air. Sorry for rambling lol hopefully this makes sense

Btw

Took some
Time to redo my tent. I hope I got it dialed in now?

yes that looks good, seems like you have it bent in a good position, just make sure your ducting is curved a little bit on the outside of the tent too so you don’t get any light leaks

 

[Cabbagelit]

Btw

yes that looks good, seems like you have it bent in a good position, just make sure your ducting is curved a little bit on the outside of the tent too so you don’t get any light leaks

Okay so today is my first day of flowering. Can i close the flaps during the dark period to keep out any light that might try to get in. Also, will the passive exhaust ducting and 1 tent vent that’s pulling air be enough for dark period?

 

[Grow So High]

Okay so today is my first day of flowering. Can i close the flaps during the dark period to keep out any light that might try to get in. Also, will the passive exhaust ducting and 1 tent vent that’s pulling air be enough for dark period?

Sorry for the late response. Yes please close that flap lol you do not want any light leaks at this stage. Depending on how big your ducting is compared to your exhaust it should be just fine.

 

[Cabbagelit]

Sorry for the late response. Yes please close that flap lol you do not want any light leaks at this stage. Depending on how big your ducting is compared to your exhaust it should be just fine.

Extended veg until tomorrow. I gotta wait for my
Dehumidifer.

 

[ComfortCreator]

Ideally you position the intakes so they can be open all the time but not let light in. This saves a lot of aggravation and stress. Get creative you will find a way.

The tents airflow needs to be enough fresh air to provide fresh co2. Additionally it needs to be as much additional airflow needed to keep humidity under 50% in flower...lights on and off.

If humidity is too high, more airflow. If too high at max you need lower humidity in the room it sits in i.e. dehumidifier...in the room.
Very easy to overlook airflow as a newbie, lots to worry about. Make sure you fix your pm issue asap. Fan at top of canopy blowing tops of plants and lights, one at bottom going across the bases works well.

 

[Cabbagelit]

Ideally you position the intakes so they can be open all the time but not let light in. This saves a lot of aggravation and stress. Get creative you will find a way.

The tents airflow needs to be enough fresh air to provide fresh co2. Additionally it needs to be as much additional airflow needed to keep humidity under 50% in flower...lights on and off.

If humidity is too high, more airflow. If too high at max you need lower humidity in the room it sits in i.e. dehumidifier...in the room.
Very easy to overlook airflow as a newbie, lots to worry about. Make sure you fix your pm issue asap. Fan at top of canopy blowing tops of plants and lights, one at bottom going across the bases works well.

I got it all dialed in now
Bro. Thanks for your input, everything you advised is what I did. I got two vents open, one fan blowing air over the plants. One fan blowing directly at my carbon filter. Inline fan circulating the air back into the room. Controlling temps in house. Temps are good at 77 degrees in tent. Humidity is not making it past 50 unless lights off. That’s will Dehumidifer will kick in soon enough. Before it was so stuffy in there getting temps at 87. PM left after a foliar spray of compost tea. Left a few leaves damaged but better that than the whole plant. No more visible PM Dehumidifer will be here tomorrow, I’m gonna start flowering.