show me your fans!! setups, mounts, hangers, filters, etc...

[Dirtbag]

bigger fan on the intake than the exhaust?

so if my tent is 54 cubic feet and I can use 2 mins to change it, I only need a 25cfm fan? that seems way too low. im super confused and backwards now.

A bigger fan yes, but not as powerful as an inline fan, I'm talking about using an axial fan on the intake. And you dont need a 25cfm fan, but you need a fan that can pull at least 25 actual cfm after calculating for ducting and filter losses. The filter and ductwork will greatly slow down the actual amount of air being moved. A 4" inline fan dialed down to 50% worked well for me as an exhaust in a 3x3 for a while, and that was with a passive 8" intake, in other words, no intake fan.

And yeah I'd use a bigger intake size UNLESS you are powering the intake with an equal size fan as the outtake, with similar airflow loss from filters on each fan.
A 4" inline exhaust with a 6" axial intake will allow the tent to vent without sucking in the walls in too crazy.

 

[CF89]

I blow the intake air directly between the lights and the top of the plants where the most heat is trapped. Then I draw this moderate temperature air from above the canopy and duct it below the plants using a seperate small fan. Works really well at keeping the whole room an even temp, and keeps all the leaves moving gently which increases gas exchange around the lower leaves.

ok this has me wondering... isnt the air just doing one big loop and staying stale? where does your fresh air come from?

 

[CF89]

A bigger fan yes, but not as powerful as an inline fan, I'm talking about using an axial fan on the intake. And you dont need a 25cfm fan, but you need a fan that can pull at least 25 actual cfm after calculating for ducting and filter losses. The filter and ductwork will greatly slow down the actual amount of air being moved. A 4" inline fan dialed down to 50% worked well for me as an exhaust in a 3x3 for a while, and that was with a passive 8" intake, in other words, no intake fan.

And yeah I'd use a bigger intake size UNLESS you are powering the intake with an equal size fan as the outtake, with similar airflow loss from filters on each fan.
A 4" inline exhaust with a 6" axial intake will allow the tent to vent without sucking in the walls in too crazy.

hmm interesting. I need to get this figured out asap so I know what size filter to order so I can order it and get it here ASAP too!!!

im trying to have the tent air and light tight, with all my air being provided via inline fans. and then a few small fans inside just moving air around the canopy and between leaves.

I was thinking the plants raised on a mesh grating about 8" off the ground.

4" inline fan on the bottom with a Y connection so I can split it into two and have it lightly blowing under my mesh grating, aimed upwards on all 4 plants.

then the 6" hung up top with the 6" carbon filter also inside the tent. the exhaust would be stronger causing a negative pressure and no air would ever escape the tent. any cracks in the tent would be sucking in air due to the giant exhaust.

or am I all wrong?

 

[Dirtbag]

ok this has me wondering... isnt the air just doing one big loop and staying stale? where does your fresh air come from?

I bring my fresh air in directly from outside, and vent it directly outside. But that's because I grow in a shed, most people bring air into the tent from a lung room, which can be the room the tent us in or another space nearby that has already been conditioned to the right temp and humidity. But most people also vent the air from the tent outside or keep a dehumidifier going in the room.

hmm interesting. I need to get this figured out asap so I know what size filter to order so I can order it and get it here ASAP too!!!

im trying to have the tent air and light tight, with all my air being provided via inline fans. and then a few small fans inside just moving air around the canopy and between leaves.

I was thinking the plants raised on a mesh grating about 8" off the ground.

4" inline fan on the bottom with a Y connection so I can split it into two and have it lightly blowing under my mesh grating, aimed upwards on all 4 plants.

then the 6" hung up top with the 6" carbon filter also inside the tent. the exhaust would be stronger causing a negative pressure and no air would ever escape the tent. any cracks in the tent would be sucking in air due to the giant exhaust.

or am I all wrong?

You arent wrong, but it's a balance. Too much negative pressure and the walls of the tent will get sucked in hard, reducing the space to grow in. Properly balanced, it should be almost neutral, with very slight negative pressure.

An you need to vent the stale air somewhere and bring in at least some fresh air from outside. Otherwise you need a source of Co2 and dehumidifiers, AC etc...

 

[redshift75]

then the 6" hung up top with the 6" carbon filter also inside the tent. the exhaust would be stronger causing a negative pressure and no air would ever escape the tent. any cracks in the tent would be sucking in air due to the giant exhaust.

or am I all wrong?

I may have missed if you said it. But do you need a carbon filter? is smell going to be an issue? You only need a carbon filter for the smell. Again if i missed you say that i apologize.

 

[CF89]

I may have missed if you said it. But do you need a carbon filter? is smell going to be an issue? You only need a carbon filter for the smell. Again if i missed you say that i apologize.

yeah smell is already an issue (personally... roomate wont mind, I just dont want to live with it, have everything permanently stinking like it, drug dogs hitting me at work, etc...) and theyre only 3 weeks old.

 

[CF89]

An you need to vent the stale air somewhere and bring in at least some fresh air from outside. Otherwise you need a source of Co2 and dehumidifiers, AC etc...

its a tent in a little corner pocket of a giant basement... im going to be venting into the basement and also taking air from the basement too.... the intake and exhaust holes are actually kind of close together. is this going to be a huge problem?

 

[redshift75]

most people bring air into the tent from a lung room

Never heard this term before but i love it.

You arent wrong, but it's a balance. Too much negative pressure and the walls of the tent will get sucked in hard, reducing the space to grow in. Properly balanced, it should be almost neutral, with very slight negative pressure.

I prefer positive pressure. but its a preference for what you are going for. In my case its how i designed the system. the positive pressure allows me to overcome the pressure drop from the filters venting back into the cavity between the filters and the inlet fan. allowing the fans to run more efficient. But thats all in the design. 99% of people are not going to worry about those things. because they are not going to try running merv 13-15 filters for a single tent. But to a standard inline/exhaust setup. For sure.

 

[Dirtbag]

Never heard this term before but i love it.


I prefer positive pressure. but its a preference for what you are going for. In my case its how i designed the system. the positive pressure allows me to overcome the pressure drop from the filters venting back into the cavity between the filters and the inlet fan. allowing the fans to run more efficient. But thats all in the design. 99% of people are not going to worry about those things. because they are not going to try running merv 13-15 filters for a single tent. But to a standard inline/exhaust setup. For sure.

I totally agree, it's only for folks trying to prevent smell from escaping. Positive pressure is better in every way imho. But only if you're runnin dank filters on the intake like that lol. Pressurization with filtered air keeps bugs and other spores and shit out of the garden.

 

[Dirtbag]

its a tent in a little corner pocket of a giant basement... im going to be venting into the basement and also taking air from the basement too.... the intake and exhaust holes are actually kind of close together. is this going to be a huge problem?

You will need at least a 60 pint dehumidifier down there to capture the moisture if you dont vent outside. Think about it, every bit of water you pour into those plants ends up in the air in the basement... it has to go somewhere or at best you will struggle with high humidity and PM and budrot issues, at worst youll get a moldy basement. And yes, intake should be nowhere near the exhaust.

As for Co2, I honestly think it will be fine without drawing in fresh air as long as you run a dehumidifier. If you vent outside, you will have to bring in fresh air from outside somewhere or you'll get negative pressure in the house, which can cause mold in the home.

 

[redshift75]

To add on to dirtbags comment. The good news about doing it in a basement is you tend to have a floor drain. For me im emptying 2 tanks 3x a day right now. Cause its in a house like everywhere in the house. But in a basement you can just get one with a hose connection for draining and you can let it run for ever.

Its most likely my genetics. But i can barely smell it. But im told im high all the time and unless its skunk or a catchy terp. i dont smell it. But if its a concern 100% get a filter. Im also of the mindset go 1 size filter up and attach to it. IDC what size hose you use. Its about surface area. will make for greater efficiency. So if you want a 6" fan get a 8" carbon filter. Thats just my recommendation.

You can have too small of a carbon filter but not really too big.


edit: 6" filters are not too bad. If i was going 4" duct id go with a 6" filter setup. But its choice. you get the right fan with the right warranty, from the right company. Wont matter if it burns out.

 

[Dirtbag]

To add on to dirtbags comment. The good news about doing it in a basement is you tend to have a floor drain. For me im emptying 2 tanks 3x a day right now. Cause its in a house like everywhere in the house. But in a basement you can just get one with a hose connection for draining and you can let it run for ever.

Its most likely my genetics. But i can barely smell it. But im told im high all the time and unless its skunk or a catchy terp. i dont smell it. But if its a concern 100% get a filter. Im also of the mindset go 1 size filter up and attach to it. IDC what size hose you use. Its about surface area. will make for greater efficiency. So if you want a 6" fan get a 8" carbon filter. Thats just my recommendation.

You can have too small of a carbon filter but not really too big.

Good advice. Has the same effect as running a fan dialed down with a speed control. I use a 10" with a 10" filter, but the fan is dialed way down to keep it quiet, so it draws air slower through the filter. Also let's me get away with a 10" passive intake considering its flowing at half speed and the filter losses etc.

 

[MIMedGrower]

That's a lot of air exchange, possibly too much. You want to aim to fully change the air once every 2-5 mins.

Personally I'd run a 4" inline fan with a speed controller on the exhaust and a 6" axial fan on the intake, or if you are filtering the intake you could just run a second 4" inline with speed controller on the intake end as well. That would be closer to ideal, and you could use the speed controllers to balance the pressure in the tent.

3x per minute max turnover with controller to turn down is standard to keep tents cool passively.

And 4x size intake to exhaust hole.

 

[Dirtbag]

3x per minute max turnover with controller to turn down is standard to keep tents cool passively.

And 4x size intake to exhaust hole.

3 times a min? That's a lot of air exchange.. I always had the "once every 2-5 min" in my head but I could be wrong.

And yeah that's about right for a passive intake, but an axial fan on a 6" intake will compensate for a 4" exhaust no problem. You could bump up to 8" passive intake on a 4" exhaust, that puts you at 5x the exhaust area.

 

[MIMedGrower]

3 times a min? That's a lot of air exchange.. I always had the "once every 2-5 min" in my head but I could be wrong.

I believe i read 5 minute exchange is minimum need for ventilated room. And yes the plants prefer less wind. But 3x is for passive ventilated tent with no a/c or dehumidifier. Intake passive. Exhaust out the building if hot.

I ran my tent like this the first 2 years to much success.

The sides will suck in pretty good at max.

 

[tomatoesarecooltoo]

bigger fan on the intake than the exhaust?

so if my tent is 54 cubic feet and I can use 2 mins to change it, I only need a 25cfm fan? that seems way too low. im super confused and backwards now.

The carbon filter will decrease your cfm, around 60% if I remember correctly.

 

[CF89]

damn, this is getting complicated and really taking the fun out of growing it. its become a full time job and requiring thousands in never ending random shit for 4 puny, struggling little plants... got me really debating how far I want to move forward with this now.

 

[Dirtbag]

damn, this is getting complicated and really taking the fun out of growing it. its become a full time job and requiring thousands in never ending random shit for 4 puny, struggling little plants... got me really debating how far I want to move forward with this now.

Growing properly is a time and money commitment. Thousand$ for sure. And you will have bad crops, you'll have crops that make you want to quit. I've seen people have bad YEARS that they eventually crawled out of.

It's like any hobby. Brewing was the same. You might be a natural but most people arent, some people get beginners luck, but most people struggle and learn eventually, or they quit.
And just like brewing, at first you spend a lot of money to produce mostly mediocre product, but over time if you do the work, you refine and grow your knowledge to the level of being able to produce an abundance of high quality product for cheap once the capital investments become a distant memory.

It can get frustrating at times, especially in the beginning, but if you stick to it you will eventually get there.

 

[MIMedGrower]

damn, this is getting complicated and really taking the fun out of growing it. its become a full time job and requiring thousands in never ending random shit for 4 puny, struggling little plants... got me really debating how far I want to move forward with this now.

Its actually simple and can be done passive with just the 6” fan exhaust likely. Need cool lightproof intake in low to the floor. Bent and black foam or stocking covered duct through the lower socks works great. And exhaust high and out of the building or at least the room. With 3x per minute exhaust i kept my old 4x4 about 5-6 degrees above room intake temp. Basically 72 toom temp. 77 flowering temp under a 600 w air cooled glass enclosed lamp with a carbon filter.

 

[Dirtbag]

Its actually simple and can be done passive with just the 6” fan exhaust likely. Need cool lightproof intake in low to the floor. Bent and black foam or stocking covered duct through the lower socks works great. And exhaust high and out of the building or at least the room. With 3x per minute exhaust i kept my old 4x4 about 5-6 degrees above room intake temp. Basically 72 toom temp. 77 flowering temp under a 600 w air cooled glass enclosed lamp with a carbon filter.

6" inline fan is kinda overkill for a 3x3 tent no? A 4" fan is almost overkill, even run passively.