Floor fans for ''some'' canopy airflow?.

Just wondering if anybody has tried using floor fans under a scrog type canopy blowing up?. I always assumed it would not work for things like wind stress or blowing moisture from pot area into canopy too much, that kind of thing. However I am struggling to add more air flow in the traditional sense due to some logistics, so hoping this could work in addition of some normal canopy air flow.

I always keep a minimum of 2 12" fans in my 4x4 tents one wall mounted blowing over tops and a cheap 12" desk fan on the floor angled upward a bit I am thinking of adding a third but I'm scarred from a pwm outbreak awhile back

I am able to have some good air flow from a vent hole i cut in a closet door at the bottom, this creates a wind effect from the negative pressure created by the exhaust fan, I also have a small fan directed midway up the plants and then another fan directed at the lights to diffuse the heat.

Yeh I used to have a 10" in the centre blowing at the vertical bare bulb and under the canopy but also did a trim of the underskirt so to speak

I had a small fan in the flower tent. It was just a 6" cheap clip on fan that I aimed between the light and the canopy. The bearings went out so I tossed it in the trash. I have 4" bottom vents opened and filtered with the carbon filter at the top of the tent exhausting air and pulling through those vents. You can feel the airflow if you stand in the tent with the door zipped shut. It was much more airflow than I thought and it's from the bottom to the top of the tent. I've never replaced the fan and get all my airflow through the vents. I've packed my tent as tight as any scrog with wall to wall greenery 3 - 4 ft high and never have any problems.

Ns950641 said:

I always keep a minimum of 2 12" fans in my 4x4 tents one wall mounted blowing over tops and a cheap 12" desk fan on the floor angled upward a bit I am thinking of adding a third but I'm scarred from a pwm outbreak awhile back

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BostonBuds said:

I am able to have some good air flow from a vent hole i cut in a closet door at the bottom, this creates a wind effect from the negative pressure created by the exhaust fan, I also have a small fan directed midway up the plants and then another fan directed at the lights to diffuse the heat.

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spliffendz said:

Yeh I used to have a 10" in the centre blowing at the vertical bare bulb and under the canopy but also did a trim of the underskirt so to speak

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xtsho said:

I had a small fan in the flower tent..

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I do appreciate the posts although it's not quite on the same track. The space isn't a tent and to cut a long story short it has a volt stepped intake/outake system, negative pressure in a meaningful amount isn't there (again saving you details).

I'm wondering if a tower fan at the middle of the space (3x10) and two floor fans, one on each end of the space would cover me for canopy airflow. I realise this would take a certain amount of loli pop to work, in order for the fans to be able to blow the moisture up and out of the canopy.

Alternatively I had another idea. I already use some under canopy ducting with ''intake'' center canopy to circulate pot height humidity into the de-heuy/airflow. What I was thinking of doing was blocking off the end hole of the ducting and then cutting some 1 inch circular holes into the ducting down the length of it. Those holes would be covered with some cheese screen. Then I will use a mid height scrog net to rest the ducting on, it will sit on level with the canopy at first flip. During stretch another net will be used about 8 inches above the first, tops will fill and be woven into the top net. The idea would be, the ducting is resting on the bottom net, running down the center length of the canopy with holes in it that can suck excess moisture directly out of the mid canopy. The out-take from that again will be pushed toward the de-heuy/tower fan where it is mixed and circulated.

Any further thoughts or ideas welcome. Logistically, the roof shape and optimal light layout does not leave much flexibility for traditional air circulation methods.

The key factor for me is any fans have to be metal. I have 0 faith in plastic circulation fans.

Nothing wrong with floor fans if that’s what you need for air flow. Just keep your floor clean so you aren’t blowing dirt and dust around.

The other idea with ducting in the canopy sounds like a waste of time energy and grow space to me.

My 1st introduction to wind burn was with a fan under a canopy blowing directly through it.
Using a screen I also noticed the root/pot temp were always a good bit cooler due to near constant extraction with vents at pot level ,a well aimed fan from the canopy and room for air to circulate makes a big difference 3/4c raise.
Does anyone monitor above and below canopy temps?

I fixed my screen to the frame which stopped air circulating, I got an old wooden curtain pole and fixed it between top and bottom bars then jammed a jug down behind it to push the tent away from the screen edge, that made a big difference to the circulating air reflected in the temperature rise, it's also great for mounting a fan on, like post #4 I also trim under the canopy it's important IMHO.

At one time I did consider bringing air in the top and venting it out of the bottom, that way it would be dry warm air getting pulled through the canopy, cool air sinks?

Thundercat said:

Nothing wrong with floor fans if that’s what you need for air flow. Just keep your floor clean so you aren’t blowing dirt and dust around.

The other idea with ducting in the canopy sounds like a waste of time energy and grow space to me.

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Yeah it would require extra effort in cleaning, I didn't take into account what Star dog said though, potentially cooling root temps too much. Wind stress was also something of concern and he seemed to have it. Did you notice any?.

The second Idea is ofc something completely different. I wouldn't say it was a waste of energy if it worked though, since you would need less W of traditional canopy airflow, which would also reduce the chance of any wind stress as a side bonus. Leds don't penitrate far (serious face) so I wouldn't be too worried about the space the ducting would occupy, stems would just cross over the top of it when being weaved.

I have never had wind stress on a plant.

Thundercat said:

I have never had wind stress on a plant.

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I've got a 5000cfm in my greenhouse working on it. But seriously I run a cheap 6" vivosun in my floor duct ports with a piece of furnace filter for cleanliness. More air always.

Thundercat said:

I have never had wind stress on a plant.

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Many doctors haven never had cancer either, I don't understand the point of your statement.

@Flowki instead of a fan under the canopy I had one at canopy level facing up to another fan pushing along the roof, physics dictate it'll circulate, remember you need space between the screen and tent wall to allow circulation.
It's now deflecting of my reflector which keeps it circulating, I can feel the draft on the floor coming back at me.

Star Dog said:

@Flowki instead of a fan under the canopy I had one at canopy level facing up to another fan pushing along the roof, physics dictate it'll circulate, remember you need space between the screen and tent wall to allow circulation.View attachment 4687383
It's now deflecting of my reflector which keeps it circulating, I can feel the draft on the floor coming back at me.

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Yeah I somewhat do that too, and always leave canopy circulation space between walls. However a fan slightly pointing up doesn't take care of moisture building or condensing between over lapping leaves. I'm trying to follow proper vpd, with higher RH you can't get away with the same airflow that was ''acceptable'' for lower rh setting (as I found out first hand). I've had to lower temps to 75f until this can be taken care of.

Again I can understand that a tent with passive intake flaps open will lift moisture up quite effectively, that isn't my situation as it's a room, so air circulation isn't as easy to get control of.

I've also constant ventilation running, when the air is circulating there's fresh air being added in and hot air going extracted, at 21/23c I'm maintaining 48/54% rh thanks to my dehum, without it rh would be around 65/70% at 18/20c

I’m in MA and sometimes the humidity can be brutal. For many years I put a box fan flat on the ground on low blowing up (using bricks to keep it up off the ground). It worked great when I was running 4 plants in a 5x5 (so I had space in the middle) never had a problem with wind burn or ill effects. Have to clean the fan before and after to get all the dust and stuff off. Passive intake on bottom from a couple points, extraction fan up top.

Actually here is a pic. It’s peeking out the bottom. I kept it on 24/7.
http://instagr.am/p/Bk89apsAcX2/

Coalcat said:

I’m in MA and sometimes the humidity can be brutal. For many years I put a box fan flat on the ground on low blowing up (using bricks to keep it up off the ground). It worked great when I was running 4 plants in a 5x5 (so I had space in the middle) never had a problem with wind burn or ill effects. Have to clean the fan before and after to get all the dust and stuff off. Passive intake on bottom from a couple points, extraction fan up top.

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I see, what in your experiance is too much canopy for the fan to blow through, 8 in, 10 inch for example?. Did you have the fan on low setting btw?.

Star Dog said:

@Flowki instead of a fan under the canopy I had one at canopy level facing up to another fan pushing along the roof, physics dictate it'll circulate, remember you need space between the screen and tent wall to allow circulation.View attachment 4687383
It's now deflecting of my reflector which keeps it circulating, I can feel the draft on the floor coming back at me.

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I like your fan mount btw ;p.

I keep it on low. I don’t think I have come across a canopy too thick for it. It definitely moves the air around good so there are no microclimates or leaves that stay stuck together. I also tend to really clean out my undergrowth because fuck larf and it keeps air moving.