Grow tent exhaust

[Kevingm1987]

Hey everyone

Question about exhaust. I currently have a two tent set up and tried using booster fans to connect both tents to only have to purchase one carbon filter and one inline fan, let’s just say this isn’t working. Temps are around 30C all the time in the big tent.

The big tent is 4x4x7 with a 315w CMH light, how big of a fan exhaust fan do you think is needed to cool this? Do you think I could get away with a 4” in-line ducted to the same charcoal filter as my other 4”? Do I need a 4” and it’s own charcoal filter? Do I need a 6” inline and filter?

All help is appreciated

[D.A.A.S.69]

Morning kevin1987, if I were you, I would go with at least a 6inch, exaust for a tent that big.

[Kevingm1987]

Thanks DAAS. Going to have to hit amazon US and venture across the border. Everything is so much cheaper than amazon CA even after conversion

[Potted]

I’ve been using a adjustable 440 exhaust fan with 6” flexible ducting,works well as long as it doesent get to hot. Just my .02$

[Kevingm1987]

Which brand? Looking at the Growneer at the moment

[Insight]

HI Kevingm1987,

I have the same size tent. When I started I had 1 315 CMH and a 6" 440cfm and carbon filter and maintained temps at around 78-80°F.
When I added a second 315 CMH to the tent....temps headed up towards 90°F. I had to add another 6" 440cfm and filter to bring temps back to 78-80°F.

So, I'd say use a 6" exhaust fan with a 315 CMH.

[Kevingm1987]

Thanks man. I bought the light and tent set up because I read I would only need 1 315W light to cover 4x4. How come you went to two?

[Redwasp]

Ive never used a cmh but I use a 1000watt hps/mh in a 4x4 tent. So i cant imagine it is enough light to cover the whole thing adequately during flowering. Probably enough for the vegetation period.

[D.A.A.S.69]

Hey kevingm1987, I got a 3x3 tent and a 315cmh and it covers it fine, but I don't know if mine would cover a 4x4 though, but I've read plenty of articles that they said that it would cover a 4x4.
I guess it depends on the light, mine ain't that big ,it came from GrowersChoice, But my tent sure doesn't hot, with a 6inch exaust.

[Insight]

Kevingm1987 ..1 315 CMH in a 4x4 tent didn't give uniform coverage, it falls off at the sides if you put the light in the center of the tent...it is great for 3x3.
I also like having more than one light due to differing plant heights.....a little easier to tailor the light distance. I have one 315 towards the rear, centered left to right the other toward the front, centered left to right.
I've been very happy with the last grow, 2 plants..total of 16 0z, and the current grow is 4 plants only 1/2 way done and looking good...

I used to use 4 300 Watt Viparspectre, that gave very good coverage but I couldn't take the blurple lighting and wanted to experiment with LEC's...the 2 315's produce a bit more heat than the 4 300W LED's, but they also draw more current......about 5.8 amps for 2 315's, and 4.6 amps for 4 - 300 W LED's.

You can definitely get away with one 315 in the 4x4 without a problem

[Kevingm1987]

Insight, going to try and see how it goes with 1 light for now. Currently got 7 autos on there that are all about 1 week old. Hopefully they all fit. I used rapid roofer and almost all plants popped which was unexpected.

I have another 2x4x5 tent that has two 600W LEDs in it. Currently it has an auto in it that’s probably about a month away from finishing and then I’m going to grow a couple photo period plants under the LEDs.

16 ounces is a pretty good haul. Any thing specific you do? I think since I have so many plants that look like there going to make it l, training may not be an option and I may just have to let them grow.

[Insight]

... Nothing special..it was my third grow...I'm in 5 gallon smart pots with coco/perlite, using Emerald Harvest Nutes and was in a Feed, Feed, Plain pH'd CalMag H2O....schedule.

I did not manifold that grow, but plenty of defoliation and LST. I think a lot has to do with genetics......the plants were......Royal OG 6 oz........and Critical Kush....10 oz.

Best of luck with your current grow.