Monkeybigbuds
- 92
- 18
I have mine pulling air from the top of the tent, where the air is hottest because of the light. I open vents at the bottom for fresh air intake.So I’ve just set up an air intake just wondering do I set it so the tent walls are sucking in or bulging out
Do you have two fans? I doubt two are necessary, especially for a 2x4 tent. There's probably less than 50 ft^3 of air in the tent and most fans can easily move that much air.Do I set it so the exhaust fan is a bit stronger than exhaust fan or other way round thanks
Yes there both 4in spider farmer fans one with carbon filter to take the sweet smell away and humidity & temp control will be running 24/7 when flowering and intake fan with speed control I just like the fact there getting fresh air from outsideI have mine pulling air from the top of the tent, where the air is hottest because of the light. I open vents at the bottom for fresh air intake.
Do you have two fans? I doubt two are necessary, especially for a 2x4 tent. There's probably less than 50 ft^3 of air in the tent and most fans can easily move that much air.
If you have a controller, perhaps a splitter could be used to run both at the same speed if they're both the same model of fan.
The AC Infinity Controller 69 has triggers for VPD so you can trigger multiple devices/equipment based on VPD values.Had anyone heard of VPD? I'm currently setting up my 3rd tent and am trying to come up with a controller for the fans to keep temp and humidity in check without causing a high VPD, which is not good for the plants.
Purely from the standpoint of physics your post is completely true. I've been a nurse for over 30 years, and we use negative pressure rooms when we want to keep the infectious things inside the room. Positive pressure is used to keep infectious things away from the patient.I’ve seen the same thing. It makes no sense. CO2 is a component of the air we breathe. Exchanging air is automatically replenishing CO2, whether done by pushing air in, or pulling air out. From FloraFlex a list of the benefits of negative pressure:
The Importance of Negative Pressure
Negative pressure plays a crucial role in creating a controlled and efficient growing environment. Here's why it is important:
- Air Circulation and Ventilation: Negative pressure helps facilitate proper air circulation and ventilation within the grow tent. When the pressure inside the tent is lower, fresh air is drawn in through intake vents, while stale air and excess humidity are expelled through exhaust vents. This continuous exchange of air helps maintain optimal temperature and humidity levels for plant growth.
- Prevention of Odor Leakage: By maintaining negative pressure, you can minimize the risk of odor leakage from your grow tent. As the air is being pulled into the tent, it creates a vacuum effect that helps contain any strong odors within the enclosed space. This is particularly important if you are growing aromatic plants, such as cannabis.
- Pest and Disease Prevention: Negative pressure can act as a natural barrier against pests and diseases. When the air is being drawn into the grow tent, it creates a gentle inward airflow. This airflow can help deter insects, as they find it more difficult to navigate against the current. It also reduces the likelihood of airborne pathogens entering the tent, reducing the risk of plant diseases.
- Temperature Regulation: Negative pressure assists in regulating the temperature within the grow tent. By creating a constant flow of fresh air, it helps dissipate excess heat generated by grow lights and other equipment. This prevents the buildup of hot spots and promotes a more even distribution of temperature throughout the growing space.
#1. True but same is true of positive pressure, just air is forced in by a fan and exits through the same vents/air leaks.
#2. True. If you need to cover up smell, negative pressure is the easiest option.
#3. Not true. The air in the tent is negative. It pulls things into the tent through every crack, vent, open zipper, and so on. When you enter the tent every bug, spore, and dust particle around is pulled into the tent. Positive air pressure does exactly what this claims negative does. It forces flying insects to navigate air currents pushing them out, not assisting their entrance.
#4. Like #1, true, but the same is true of positive pressure and active systems exchange air even more effectively.
Negative pressure is far superior to no ventilation at all. Excepting odor removal, positive pressure does the same things. Using a hybrid system with passive ducting above lights allows positive pressure to force hot air out, or place the same passive ducting to bring in cooler air allows negative pressure intake above lights to pull heat out. Active systems allow you be either negative or positive depending on what works best at a given point, or even allow you to match atmospheric pressure and still move tons of air.
In my limited experience, I found active, with cool air coming in low, and hot air being forcibly extracted from above, to be by far the best method for removing heat. Active systems have one addition advantage that I’ve never seen mentioned, redundancy. If, and when, one fan fails, the other fan/s still allow for forced air movement. That might be the difference that saves a crop.
The panty hose is a good idea. I live in an old house, and it is always somewhat dusty. I never thought about using nylons as a pre-filter.I run full negative pressure on all my tents, all bottom flaps open and exhaust and filter at the top,
My tents are always pulled in even with all flaps open, in my 4x8 I have 4 flaps and I recently used one of the tent inlets to add in another piece of 6” flex ducting just to let a bit more air as well
The 4x4 has 1 flap so I added 2 of the 6” ducts as inlets at the bottom in there as well
As long as you don’t restrict the inlet you’ll have plenty of air exchange to remove heat and humidity as needed if you think it’s still too much negative pressure just throw in a 6” duct on a bottom tent inlet (I cover my ducts with panty-hoes so no bugs can get in through the ducting, at least that’s my method lol)
I’ve also heard negative pressure stresses the plants more than positive but I’ve never tested it myself I’ve always ran negative, tried with an inlet fan but it seemed to be causing more problems than it was solving so I just went back to the passive intake methodPurely from the standpoint of physics your post is completely true. I've been a nurse for over 30 years, and we use negative pressure rooms when we want to keep the infectious things inside the room. Positive pressure is used to keep infectious things away from the patient.
Even building PC's keeping positive pressure in the case helps to keep dust and debris away from your sensitive components.
Being this is my first ever grow, I wasn't sure if there was some obscure reason for the use of negative pressure that eluded me. So I just did what I was told, and it has worked out. But, as you say, it almost certainly would have worked out either way.
When you say that you use an active system, do you have different sized fans? Like say a 6" for intake, and a 4" for exhaust so that you maintain positive pressure?
I'm not dissatisfied with how things have gone with my negative pressure, and I have no plans to change it. Other than to steal your pantyhose trick. But it is a subject that vexed me from the start. I mean either way you are taking CO2 laden air and placing it in the tent. And if you use a CO2 tank to bolster the level around the plant(s) positive pressure might be better since negative pressure would just exhaust more CO2 into the room and away from the plant(s).I’ve also heard negative pressure stresses the plants more than positive but I’ve never tested it myself I’ve always ran negative, tried with an inlet fan but it seemed to be causing more problems than it was solving so I just went back to the passive intake method
It’s just something to cover it, and damn do they get dusty, and my wife is a CLEAN FREAK she vacs the house twice a day, sanitizes every counter etc, and those nylons still dust up but we live out in the country so between everyone rippin 4 wheelers etc it builds up, I haven’t done a full tear down in like a year, really need to do one eventually lol, just been bleaching the inside while wearing a full face respirator between runsThe panty hose is a good idea. I live in an old house, and it is always somewhat dusty. I never thought about using nylons as a pre-filter.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?