Question about ventilation

vitalsine said:
I had a quick question about ventilation.



On a side note, I know the T8 is super overkill for a 5x5x7, but when I get my other tents setup, I plan to use the T8 to exhaust multiple tents. I'd be running it to the 5x5, a 4x3x6 and a 2x2x4. I'd need an additional 200 CFM (roughly) for the other tents, possibly more with the additional ducting, but I'd still be way under the total CFM of the exhaust fan. These other tents will have a passive intake, just drawing from the ACed room. Or I am considering removing the T6 as an active intake on the 5x5 and repurposing it as an exhaust for the other tents, as I'd have to run an additional 10ft or so of ducting to provide exhaust for them if I use the T8. Ultimately that doesn't really matter though because I still won't be anywhere near needing 800CFM, even if I had to add 100% for the other tents. The T8 is mounted right next to the 5x5 and maybe about 6 ft of ducting runs directly out the window. The only real plus to repurposing the T6 would be that I could take maybe a 1 amp load off the panel by not having to run the T8 at full speed.

If you guys need any further clarification, let me know. I appreciate any help or comments!
Click to expand...

Just remember with one fan and multiple tent extraction if the tents are not the same size your going to get a big difference in temp from one tent to another.

The fan will divide equally on a Y splitter but the tents are not equal in size. Ones 175 cubic foot and the other is 72 cubic foot.
That means your smaller tent (4x3x6) is exchanging air 2.4 times faster than the bigger tent which means its going to be considerably cooler.
If the smaller tent is going to be veg tent and your running LED its more important for that tent to be warmer. Or I should say you can get away with 78 in flower but in veg you are more likely to have problems at lower temps.

Filters also need to be the same size or your fan will pull through the path of least resistance.
 
coreywebster said:
Just remember with one fan and multiple tent extraction if the tents are not the same size your going to get a big difference in temp from one tent to another.

The fan will divide equally on a Y splitter but the tents are not equal in size. Ones 175 cubic foot and the other is 72 cubic foot.
That means your smaller tent (4x3x6) is exchanging air 2.4 times faster than the bigger tent which means its going to be considerably cooler.
If the smaller tent is going to be veg tent and your running LED its more important for that tent to be warmer. Or I should say you can get away with 78 in flower but in veg you are more likely to have problems at lower temps.

Filters also need to be the same size or your fan will pull through the path of least resistance.
Click to expand...
pretty sure he knows he needs a fan in each tent.
 
vitalsine said:
To each his own I guess lol. I'm going to leave it on til I set up the other tents, then I'll be opening the vents and putting some sort of filter over them. Your the only person I've talked to that has a difference of opinion, but I'll take it haha. Thanks dude.
Click to expand...


Hey dude, I was not trying to be jerk, I was just trying to tell you that real science says pushing air into a place where one wants to create a negative pressure zone simply amounts to one wasting electricity, while also unnecessarily pushing heated air into that negative pressure zone. Anyway... have fun, and happy growing!
 
piratebug said:
Hey dude, I was not trying to be jerk, I was just trying to tell you that real science says pushing air into a place where one wants to create a negative pressure zone simply amounts to one wasting electricity, while also unnecessarily pushing heated air into that negative pressure zone. Anyway... have fun, and happy growing!
Click to expand...

Don't sweat it, I didn't take it that way haha. Sorry if I came off like a jerk who thought you were being a jerk! haha
 
coreywebster said:
Just remember with one fan and multiple tent extraction if the tents are not the same size your going to get a big difference in temp from one tent to another.

The fan will divide equally on a Y splitter but the tents are not equal in size. Ones 175 cubic foot and the other is 72 cubic foot.
That means your smaller tent (4x3x6) is exchanging air 2.4 times faster than the bigger tent which means its going to be considerably cooler.
If the smaller tent is going to be veg tent and your running LED its more important for that tent to be warmer. Or I should say you can get away with 78 in flower but in veg you are more likely to have problems at lower temps.

Filters also need to be the same size or your fan will pull through the path of least resistance.
Click to expand...


Good point. I didn't think of that. I will test a few things out, maybe using more ducting with more sharp corners will help level things out from one tent to another. Since I'd want the veg tent warmer I could just use more ducting or something to offset. I'll play around, and if I need to I'll grab a small inline for the 2x2.
 
JoeBlow5823 said:
I recently installed these top of the line, state of the art filters on my intakes. They dont catch everything but its a hell of a lot better than nothing.
View attachment 4648353
Click to expand...


Hey it works, and really it is needed, cause after installing one you can actually see how much nasty shit would have gotten in and all over your buds without one! Anyway, on all my intakes I use at least Merv 4(s)
 
JoeBlow5823 said:
Shit. Ya got me. Yeah i would never try to run one fan for multiple tents. Id rather run two cheap ones than one expensive one.
Click to expand...

haha. Yea, this is still my first grow. I swear I did see some diagrams online about running one fan for multiple tents, but who knows who the hell made those. So much mixed info out there, that's why I prefer a forum like this, you can get multiple opinions and make the decision on your own... rather than just taking the opinion of one guy who wrote a blog post about it. lol.
 
JoeBlow5823 said:
Shit. Ya got me. Yeah i would never try to run one fan for multiple tents. Id rather run two cheap ones than one expensive one.
Click to expand...
I run two tents off one fan and it works but all things are equal on either side, duct length, filter size .
Was the only way I could get cfm low enough in winter with the crazy quiet fan I have and the temp controlled variac which has an idol speed of 45%. Otherwise I would use a fan per tent. AC infinity would of offered more control but those ac infinity fans were not available over here at the time and low db is my number one priority.
 
Here is a pic I took sometime last year, that shows what even a cheap filter, (one of them frost-king ac filters, rubber banded to a 6 inch intake), will keep from getting into ones grow space in just 30 days. And as a side note, my tents are in a clean room, no one goes in there but me when I need to do shit!

filter.jpg
 
coreywebster said:
I run two tents off one fan and it works but all things are equal on either side, duct length, filter size .
Was the only way I could get cfm low enough in winter with the crazy quiet fan I have and the temp controlled variac which has an idol speed of 45%. Otherwise I would use a fan per tent. AC infinity would of offered more control but those ac infinity fans were not available over here at the time and low db is my number one priority.
Click to expand...

So you're saying I should just get another 5x5? Don't tempt me. My girl would kill me! LOL. As it is, I'll be putting both breakers on max load pretty much with the gear I have... so another cheap low watt fan is what'll be in the books.

5x5 w/ 4 SF-2000 (flower)
3x3 w/ 2 SF-2000 (flower)
1x3 (x2 it's two levels) with 50w T5 up top and SF-1000 down low (clones / seedlings / early veg)
2x2 w/ 1 SF-1000 (veg)

I've also got some of these


Thinking maybe I put 2 SF-1000 in the 2x2, then the T5 down low and these light strips up top for seedling/clones.

I'll be pulling 15.8 amps off my main breaker with all that shit (+/- depending on circulation fans, humidifier, etc. but they don't bring much to the table). This calculation is also based on the idea that the inlines would be running at 100%, so I have another amp or so to play with before I hit 16 amps which would be 20% load on a 20 amp circuit. Then my subpanel is dedicated to just the AC/Dehu, which if ran together would be 14.7 amps, also a 20 amp circuit. This gives me about an amp to play with as well, could always stick another inline on there. Def no room to get more lights going though.

Anyway, I'm going off subject haha.
 
In a 2x2 in veg 1 sf1000 is overkill , you only need like 15w per square foot. Unless your planning on splitting the 2x2 vertically you wont need two sf1000s and if you do you will have to seriously dim
 
coreywebster said:
In a 2x2 in veg 1 sf1000 is overkill , you only need like 15w per square foot. Unless your planning on splitting the 2x2 vertically you wont need two sf1000s and if you do you will have to seriously dim
Click to expand...

I overshot a bit haha. I already have them so I gotta put em to use somewhere, dimmed or not. I know I don't need anymore in the 3x3 if I run 2 2000s. Plan would be for the 2x2 to be ready to flip when they come out. Kinda plan on alternating the 3x3 and 5x5 so that I'm not harvesting both at the same time. It'd be staggered. I'll figure it out one way or another! I just thought it best that they live under the same/similar light conditions before they get flipped in the bigger tents.
 
HVAC filters on the intake vents is a great suggestion btw... and don’t be afraid to just cut one if you have a spare laying around.

I do the same to fill the filter box I made for an air compressor, too.
 
piratebug said:
Hey dude, I was not trying to be jerk, I was just trying to tell you that real science says pushing air into a place where one wants to create a negative pressure zone simply amounts to one wasting electricity, while also unnecessarily pushing heated air into that negative pressure zone. Anyway... have fun, and happy growing!
Click to expand...

@piratebug Could you share a pic of how you attach the merv 4s to your tent? I bought a few and just curious how your using them.
 
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