Exhaust fan too powerful?

[Spaidan]

Hello Growers

May be a stupid question, but is it possible for an exhaust fan to be too powerful for an indoor setup. 

 

A year ago when I started growing indoors I had an exhaust fan in the top of my 2x2 grow tent. For the first few grow attempts my plants were unhappy and yellowing and no idea why, I looked at my soil, my water, basically everything that could cause this problem but absolutely nothing I did fixed the problem. I tried many different thing yet I got the same result. 

 

It wasn't until I decided to turn off my exhaust fan and only leave a normal oscillating fan outside bottom of my tent to push air through the intake vents therefore forcing the air out the top hole where the exhaust fan was. Since then all my problems were resolved. I was extremely confused as I always thought the more airflow the better right? Outside in nature there's so much wind and constant airflow I would never assume that was the problem. 

Would like to know if anyone could give advice on why this is? Am I crazy? Is there such a thing as too much airflow, or too much negative pressure in the tent not allowing the plants to "breathe" because theres just too much airflow? 

Sorry if this sounds extremely stupid. Just very curious. Because since I turned off the exhaust all my problems disappeared. Was thinking about turning on the exhaust again because I need to exhaust the hot air building up from the lights. I don't have a speed controller on my exhaust fan. 

Basically would just like to know if there is such a thing as too much constant airflow in the tent. My bottom fan is oscillating so it gives a few seconds of rest for the air intake into the tent. 

Thanks guys

 

[Dookie69]

Air flow in this game is the hardest element to get right. Everything else is tangible, measurable and visible.
Air flow is invisible and impossible to observe. It affects temperature, CO2, odours, stem strength and humidity.
Too much buffeting by a fan is bad for leaves. Bear in mind outdoors wind comes and goes, but a fan placed too close to a plant will relentlessly buffet it around. I think it’s ability to photosynthesise is compromised, and it starts drying out (stand to be corrected here)
What I do is set my phone to record video, then place it in the tent to record what’s happening in there with air movement. This should tell you a story.
If your extraction is the culprit then try extending the ducting, or give it a few tight turns to reduce its air flow, and observe with recording if it’s helped.

God luck


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[Spaidan]

Awesome thanks for the help dude, much appreciated

[Ill_Evan]

19 hours ago, OrganicGrower_ZA said:

is it possible for an exhaust fan to be too powerful for an indoor setup.

What size and type of exhaust fan were you running? 

[Spaidan]

26 minutes ago, Ill_Evan said:

What size and type of exhaust fan were you running? 

[Dookie69]

It’s possible that fan isn’t powerful enough, especially for South African conditions. I think you have heat / humidity build up because the fan can’t suck fast enough. You should try an in-line 100mm ducting fan. I’ve read you can get them from electrical supply places like AC/DC if you looking for a good price.


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[Ill_Evan]

@OrganicGrower_ZA so you get 300m³/h of air transfer with that fan. For your tent you want to do at least one transfer of air a minute which is the recommended amount. So you need a fan that can transfer the 8m³ of air in your 2x2x2 tent once every minute. So if your fan does 300m³/h then it does 5m³/min, which means it actually under performs for your tent specifically although I'd say it's good enough if just for simple air transfer. 

 

[Prom]

2x2.... and you use a bath room fan?  if a guy in a grow shop recommended you that setup, go there and show him a birdy.  

I have a 'few' more 6 inch inliners in my 2.4x2.4 and they never stop. Also run my big one max 3/4 area, no space to access otherwise.

 

To know if you have enough air exchange, do a simple test. When your lights go off and your humitity goes down with the temperature, and not up, you have enough air exchange... otherwise.. add more vent capacity. A 2x2 will turn your room into a turbine testing facility... sounds at least like it 

That is just the exit side on my big tent

 

Short addon to the turbine factory. 

That is no joke, if you live in the same area, as your tent(s). A silent inliner might be way better choice... and always go one in, one out. If you want to fill your 2x2, 2 x 150mm in and 2 x 150mm out.. a td-500 is around 3000 rand. I started to change my cheap noisy ones with silent versions. They are a bit more bulky 

But they are waaaaaaaay more silent.. what you pay you get less noise for

Edited January 27, 2021 by Prom
addon

[PsyCLown]

Is that 2m x 2m of 2ft x 2ft?

Big difference, since we are in SA I feel we should be using meters. I have a feeling its feet, so 60cm x 60cm  which is a very small tent?

 

 

@Prom if you need more fans, for a little more it may be worth considering the AC Infinity fans, they're really awesome and very quiet as well!

Comes with a very nice controller with a RH and temp probe: https://zephyrfarms.co.za/product/ac-infinity-cloudline-t6/

 

I have two and love mine! Use them for exhaust.

[Prom]

27 minutes ago, PsyCLown said:

Is that 2m x 2m of 2ft x 2ft?

Big difference, since we are in SA I feel we should be using meters. I have a feeling its feet, so 60cm x 60cm  which is a very small tent?

 

 

@Prom if you need more fans, for a little more it may be worth considering the AC Infinity fans, they're really awesome and very quiet as well!

Comes with a very nice controller with a RH and temp probe: https://zephyrfarms.co.za/product/ac-infinity-cloudline-t6/

 

I have two and love mine! Use them for exhaust.

 those are some sexy inliners . My heart skipped a beat when i saw the price.  But thanks for the link, i like options 

 

Yes, i agree 100%, for 2 feet by 2 feet, two bathroom fans would do  

 

 

[Spaidan]

2 hours ago, Prom said:

 those are some sexy inliners . My heart skipped a beat when i saw the price.  But thanks for the link, i like options 

 

Yes, i agree 100%, for 2 feet by 2 feet, two bathroom fans would do  

 

 

It's 70cm x 70cm x 1.6m

[Prom]

46 minutes ago, OrganicGrower_ZA said:

It's 70cm x 70cm x 1.6m

Different story  but still just one fan for in and out?

[Spaidan]

5 minutes ago, Prom said:

Different story  but still just one fan for in and out?

Yes I've been growing with one oscillating fan outside my tent pushing air into the intake vents forcing air out of the hole at the top of my tent. It's been working great until I've recently added the new quantum board. My average Temps use to be around 24-25 with a relative humidity of 50 percent which isn't bad conditions. But now the past couple of days it's been sitting at 29 degrees with 40 humidity. And this is with the QB board dimmed down to 40 percent. If I had to blast the QB board at full intensity my temps will go just over 30. When I turn the extractor on it coolsthe tent down only by 1 or 2 degrees. Keep in my mind this is a small office grow.

[Dookie69]

What is the ambient temp and humidity outside the tent? Do you exhaust back into the same space as the tent or to the outside?

If it’s an office, are there big changes between day and night room temperature and humidity?

Thing is if your temp, humidity and “freshness” of the intake air are not right, you will struggle to lower / raise accordingly.


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[Spaidan]

 

52 minutes ago, Dookie69 said:

What is the ambient temp and humidity outside the tent? Do you exhaust back into the same space as the tent or to the outside?

If it’s an office, are there big changes between day and night room temperature and humidity?

Thing is if your temp, humidity and “freshness” of the intake air are not right, you will struggle to lower / raise accordingly.


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This is the problem I face, all the air gets exhausted back into the same room. The office hardly has any ventilation at the moment. It does have an aircon on the wall which I do intend on fixing. The aircon will take some of the hot air out and make it cooler in the room however I cannot run the aircon all day due to electrical bill. 

However with the setup how it is I've achieved some decent results. It's just because of the new QB 120w it's added some extra heat. Office temp is basically the same as inside the tent. I would love to take ducting and exhaust the air out but due to certain circumstances I cannot do that at the moment. 

I'll add some pics of older harvests of mine achieved with my current setup. 

Sorry for the shit blurple Light, was a bad purchase as a beginner. 

[Dookie69]

Impressive!
Can the driver be taken off the board and placed outside the tent? That will help a lot, and a better fan. If you still have too much heat or humidity you will have to run the ac here and there. You’ll probably have excessive heat during lights on and excess humidity when lights are off.
The struggle is real.


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[Prom]

If the temperature is the same inside the tent as in your office, cant do much. If your tent is hotter... add more ventilation to your tent!! 

(As if i speak chinese ) adding light means you also add ventilation to get rid of the extra heat you brought to your tent. If you dont know why you do that, read up on the conservation of energy  

I suggest you fix that AC asap...