Grow Tent Air Intake Light Baffle

[odam2k]

This was originally posted in another large thread most people won't ever see, so I'll put it in it's own post in case anyone is interested...

Today's mini project, a light baffle for my Flower Tent air intake.

You can see how much light leaks OUT, so it worries me that light is leaking IN when it is supposed to be dark in there...

I took some measurements, and using the latest CAD system, came up with these engineering drawings...

To make this project, you're going to need to make a visit to the dollar store...
First BLACK foam board, I bought two, not knowing how much I'd need, but this baffle used only one sheet.

Some BLACK duct tape to assemble it....

You will also need some Velcro Tape, we'll use that to attach the box to the tent...
I didn't have any, so still need to go buy some...

So now I needed to figure out the pattern to cut out so that I could fold it together... Again, using the latest CAD system, I created more engineering drawings...

And here it is transferred to the foam board... For the folds, I cut the paper on one side, and put duct tape on the other side to prevent it from tearing... You can see the cutouts at the ends for air intake...

Folding it up.... except the top, I'll leave that open so I can add the baffles inside.

And here are the baffles to prevent the light from shining directly through...

Now fold the top down, and tape it all up...

And finally, hold it up to the tent to see if any light comes out the ends...

I'd say it works!

I still need to add a "flap" all around the edges, it will simply be a flap of duct tape with the velcro attached to it so that you just place the box against the tent, and press the flaps on all 4 sides of the vent, and voila, the air can get in, but the light can't get out...

I'll add a couple more pictures once I get the velcro tape and install this.

 

[TorturedSoul]

Wow, that's way fancier than taping a two or three cardboard boxes together in an offset orientation, or one with a couple adjustable elbows connected to it in an "S."

Nice job! Thank you for sharing your idea with us.

I am surprised that none of the grow tent manufacturers have ever bothered to sell an add-on accessory package for this purpose. I'd think it would be a money maker for them. Most of them seem to treat ventilation as a bit of an afterthought. I mean, sure, they include vents - and quite a few, some of them. But then they place a great deal of emphasis on their product being "light-tight" while simultaneously including lower vents that, in order for them to function, leave some pretty <BLEEPING> substantial paths for light to potentially enter the grow space.

Kind of makes a person wonder. . . .

 

[TurboBucket]

Certainly put some time into that as well. How much does it reduce the intake opening? Looks like it's just the ends that are open? If it's less than 50 sq in a piece of 8 in duct with a couple of bends or a bend and a long leg would keep the light out as well.

Definitely a cool piece though. Well done.

 

[odam2k]

I have a 6" fan pulling through a carbon filter, exhausting out the top of the tent through a 6" duct. I also have a 6" duct about 2 feet long, through a floor level port, bent into an S shape, you can see it at the bottom of the first picture. This is for intake.

I don't know how much this will restrict the air flow through the larger vent, but any extra air flow is good, and I want to make sure it stays dark in there when it is supposed to... Once I get it installed, I'll try to see if I can detect a difference, although I'm not sure how I'd actually measure it...

 

[TurboBucket]

although I'm not sure how I'd actually measure it...

Are the openings in the ends of the new box equal to the opening you are covering? Was my initial question. As tortured soul mentioned most manufacturers don't seem to make large enough passive intakes, so I was curious if you had reduced that further.

As far as light leaks are concerned I just keep the lights off during dark periods. The zippers always have pinhole leaks.

 

[odam2k]

Are the openings in the ends of the new box equal to the opening you are covering? Was my initial question. As tortured soul mentioned most manufacturers don't seem to make large enough passive intakes, so I was curious if you had reduced that further.

As far as light leaks are concerned I just keep the lights off during dark periods. The zippers always have pinhole leaks.

Yes, the total size has been reduced to about half... I do have two more holes marked out on the outside that I can cut out if I absolutely must, but they may not be as lightproof as the ends... Perhaps slots instead of a big hole...

Right now, my flowering is done in the one tent I have, with Veg right beside it, so lights are on 24/7 in the room itself. This will change with the addition of another tent in the coming months, and then it won't be a problem... So far this tent has no light leaks when buttoned up, but it's only a month old I'm actually very impressed with the quality, glad I ordered the 1680D version...

 

[TurboBucket]

Nice your on the right track then.

I have an Apollo and a vivosun. Both 4x4's. Neither are actually 48" inside, the vivosun is bigger 45" but only has two passive intakes and they are all smaller than the three intakes on the Apollo.

The Apollo leaks at the zippers, both the stitching and through the zipper teeth if the inside flaps aren't overlapping properly. They vivosun does the same thing and also leaks where they stitched an accessory pocket on the inside.

They were both leak proof for the first year or so. But I've heard of folks getting the expensive gorilla tents and still ending up in the same boat. So for me it's easier to just leave the room dark over night.

 

[TorturedSoul]

Once I get it installed, I'll try to see if I can detect a difference, although I'm not sure how I'd actually measure it...

It's rougher than rough, but: Remove your alteration. Adjust your fan speed to get a slight negative pressure (tent walls slightly drawn in). Reinstall your alteration and see if the tent appears to be under a higher negative pressure (tent walls drawn in more than before). If so, you know that your alteration has further impeded the airflow.

Be more like a "pass/fail" then a degree of difference, or however you want to phrase it - but it would tell you something.

 

[odam2k]

It's rougher than rough, but: Remove your alteration. Adjust your fan speed to get a slight negative pressure (tent walls slightly drawn in). Reinstall your alteration and see if the tent appears to be under a higher negative pressure (tent walls drawn in more than before). If so, you know that your alteration has further impeded the airflow.

Be more like a "pass/fail" then a degree of difference, or however you want to phrase it - but it would tell you something.

Great idea... Since posting, I remembered I have a handheld anemometer I used to use when I flew model aircraft to check wind speed... I was thinking maybe hold it where the air exits the ducting.

If that fails, I have a backup plan now, thanks

 

[odam2k]

I can't test it till the lights come on at 5am, but I did some measurements...

The vent opening is 5 1/4" x 17 1/2", or roughly 92 sq inches
The 2 Box end openings are 2 1/2" x 3 1/2" or a total of 17 1/2 sq inches

Bit of a problem...

I made the end holes larger, 5 1/2" x 5 1/2" or a total of 30 sq inches...

Better, but far from ideal... Also, as I contemplated cutting more holes, it occured to me that it's going to be the spacing between the baffles that determine the air flow, and adding more holes to allow air in won't make any difference.

So, on that note, this may not be an ideal solution, but if you just want to add a bit more air flow, and are concerned about light, as is my case, then I think it's fine... I also use a 6" duct for inflow of air... this is just to add more...

If you need more airflow, then perhaps this project will at least give you something to work from, perhaps scale it up to a larger box with more spacing between the baffles...

 

[odam2k]

I found some velcro, left over from my R/C days...

The "flaps" are made with tape, I used black on the inside, and silver outside, cause I have lots of that...
I just attached the velcro to the flaps... I think once installed, this is going to stay put, and may even be a pain to remove... We'll see, lights on in just over 2 hours (5am) and I'll give it a go...

 

[odam2k]

Good news, I think...

I used a small hand held Anemometer to measure the wind speed coming out of the ducting, which is exhausted from the tent.

I took 6 readings, 3 with the fan on 100% and 3 at 50%.
The 3 consist of having the vent covered completely, open completely, and with the box installed.

	Fan at 50%	Fan at 100%
Vent Covered	5.0 m/s	7.5 m/s
Vent Uncovered	5.5 m/s	8.6 m/s
Light Box in place	5.0 m/s	8.5 m/s

Keep in mind I also have a 6" duct for air intake.

At 50% the vent probably isn't as effective anyhow, the duct likely provides enough inflow... However, at 100% the box has almost no effect on the amount of air being pushed out of the tent.

I'm calling it a success!

 

[odam2k]

It's hard to see, because it's dark, but that's the point!

The Air Intake light box has blocked the light almost completely, I don't see any....

You CAN see the light leaking out of the Duct I'm using for an intake which has a tight U shape.

 

[odam2k]

Just a quick update, this box has been working like a charm on the side of the tent, providing plenty of air exchange...

The other day I made up something similar, using the same black foam board, for my apartment window. I have a box-fan in the window to draw cool air into the room (until it's time to put the air conditioner back in service) and my 400W Veg light is only about eight feet away, and right now is using an HPS bulb until I can replace my MH bulb, so the light is VERY YELLOW, quite abnormal, and with the box fan, visible to anyone who looks up at the window!

So I basically just started taping pieces of black foam board together until I had something that blocks the light, at least from wherever we've tried looking... I didn't get any pictures when I put it together because it's very temporary, and ugly, but it is working!

The box fan sucks air in from outside, the "hood" deflects it downward, where the pedestal fan blows the cool air toward the veg plants...

Gotta love this stuff... foam board and duct tape

 

[odam2k]

Repurposed the black foam board, and fit the air conditioner... Building management said we are not allowed to have air conditioners hanging out windows above the first floor... so the air con just butts up against the screen, and is enclosed to allow proper operation...

 

[TorturedSoul]

Building management said we are not allowed to have air conditioners hanging out windows above the first floor...

What's the stated motivation for this? Owner of the building pays electricity? Doesn't like climbing stairs, so he wants everyone living above the ground floor to go live somewhere else so that pigeons can be the only inhabitants up there? He wants someone's jurry-rigged solution(*) to fall out of their window just as he's walking by underneath, thereby putting him out of his misery? Or...?

(*) I just realized that this one might be taken as a dig about your modification. It is not; I'm assuming that you've tested yours for stability, overheating of the compressor, etc.

 

[odam2k]

I guess they don't trust peoples installations, it's ok to put an air con in the windows on the balcony, just not any that would allow the unit to fall I guess... It was not aimed at me, but was a blanket "enforcement?" of an existing rule...

 

[odam2k]

I'm assuming that you've tested yours for stability, overheating of the compressor, etc.

I am surprised that it's working as well as it is... well, perfectly... lol...

It's been 31C out, and the grow room stays about 26C when both lights are on, and 24C when just the veg light is on...

In fact, I've got the grow room door cracked open a bit to let some cool air into the apartment...

My original design for mounting the air conditioner "inside" the window screen involved duct work and inline fans, blowing air into the side of the air con to cool the compressor, but it is getting enough air in through the screen.
And of course, the black foam board is great for preventing light showing outside too...