Grow Box Venting Question (PICS)

So I made my own flowering box out of 2x4's and black plastic. Off to the right of my flowering box I have my clone / veg area. As you can see from the pictures, this is all in my closet.

The only problem I am having is that I have exhaust air out for the lights but no air intake. I can see the plastic suck in when i turn the exhaust fan on, which is good it shows that its a completely closed unit but its getting very little air in. I don't know how to make air intake wthout letting light in during dark period because my clones are right next to the box. How would I go about doing this?

I thought about putting a venting tube in the top of the box, running along the side down to the floor where a fan is blowing it to the plants. Will light get in down the venting tube ? Im not sure how this works hehe

what type of lights you using?

plantz said:

what type of lights you using?

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Plants are sleeping right now so I couldnt snap a pic of the inside but I am using a 150W HPS with a built in ballast and a 4 bulb 2 foot long T5. Soon I'm getting a 400w HPS cooltube in place of the lights I have now. But I have to wait on that for a little...

use some of that aluminum t-fin you used up top.

stick in side wall, near the bottom and where it comes out of the box make it turn dowards both on the inside and outside of the box. no light should get in that way, and if you are using a fan, and the rest of the area is sealed off, air will surely pull through with no problem.

and since heat rises, it is better to vent out at the top of your box, and in at the bottom. that way the air coming into the box is cooler then the air going out. that will help keep the temperature from getting too high. unless your exhaust air gets trapped in your closet it and eventually becomes the only avaible intake air.

eric1589 said:

unless your exhaust air gets trapped in your closet it and eventually becomes the only avaible intake air.

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That is what I'm afraid of. But what I am going to do is install the ducting at the bottom as you suggested except not on the side of the box but in the front where the box meets with the closet door, it should pull fresh air through the cracks of the door into the box instead of pulling air from the inside of the closet.

if you loop your exhaust venting and make it black lined then no light gets in

jjf1978 said:

So I made my own flowering box out of 2x4's and black plastic. Off to the right of my flowering box I have my clone / veg area. As you can see from the pictures, this is all in my closet.

The only problem I am having is that I have exhaust air out for the lights but no air intake. I can see the plastic suck in when i turn the exhaust fan on, which is good it shows that its a completely closed unit but its getting very little air in. I don't know how to make air intake wthout letting light in during dark period because my clones are right next to the box. How would I go about doing this?

I thought about putting a venting tube in the top of the box, running along the side down to the floor where a fan is blowing it to the plants. Will light get in down the venting tube ? Im not sure how this works hehe

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http://organic-hydroponicsupplies.thebigtomato.com/shared/StoreFront/default.asp?CS=tbt&StoreType=BtoC&Count1=435497462&Count2=352637887&CategoryID=48&Target=products.asp

Here is a link to a vent you can use, there are a ton of vents that don't reflect light, but why not just put a hole above the flower area to pull air in instead of the wall?

Mortloch said:

http://organic-hydroponicsupplies.thebigtomato.com/shared/StoreFront/default.asp?CS=tbt&StoreType=BtoC&Count1=435497462&Count2=352637887&CategoryID=48&Target=products.asp

Here is a link to a vent you can use, there are a ton of vents that don't reflect light, but why not just put a hole above the flower area to pull air in instead of the wall?

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Well I thought of that but won't that let light in? I have my clone area with 2 fluoro's setup just to the right of my flower tent. I poke a few holes in the top and sit inside with everything shut and see if any light comes in, that would be the simplest solution. Or I could punch a few holes in the left side of the box where the box is about 3" from the wall, it should be completely dark back there.

jjf1978 said:

Well I thought of that but won't that let light in? I have my clone area with 2 fluoro's setup just to the right of my flower tent. I poke a few holes in the top and sit inside with everything shut and see if any light comes in, that would be the simplest solution. Or I could punch a few holes in the left side of the box where the box is about 3" from the wall, it should be completely dark back there.

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I added a passive air intake. It is a 4" diameter dryer duct that enters through the top of the unit and runs down the side half-way to the floor. There is no fan sucking air in, only a weak inline exhaust fan (not sure how many CFM) pushing air out through another duct. The air is sucked in passively because the fan blowing air out creates a vacuum. The air comming in is comming in slowly though...

I measured the temperature of the air being taken in and it is around 81-82°F. The Air being pushed out is measured around 90-96°F. The actual ambient temperature of the unit is at 90°F mid-level (right where my plants tops are sitting) and around 85°F on the floor when the lights are on. When the lights are off the temps are at 74-76°F.

So what more can I do to keep the temps down? Is the passive air comming in too slow, should I add a fan to it to suck air in faster? Or do I need to blow hot air out faster, seems like its sitting around in there too long...

Any advice would be greatly appreciated

I also have a fan circulating air around the box but I do not have a fan blowing the hot air off the lights to the exhaust. I'm guessing adding that and a more powerful exhaust will help.

Also wanted to add that I'm growing Sativa's, not sure if they can withstand higher temperatures but they are growing pretty decent, the budds are about where they should be for their age...just figured they may grow a little faster/larger if I could keep the temps down.

have you thought of an air conditioner???? i just found a link to the cheapest one at $199 for a 8,000 btu! im thinking about ordering it and giving it a try. how big is your room your growing in?

DankJWeeks said:

have you thought of an air conditioner???? i just found a link to the cheapest one at $199 for a 8,000 btu! im thinking about ordering it and giving it a try. how big is your room your growing in?

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Dimensions are 4L x 3W x 5H
would need ~72 CFM rated fan to move the air out of it every minute I think...Whats the CFM calculation again?

Also I did think of an AC unit but wouldnt that take up a ton of wattage, I want to reduce that as much as possible.

jjf1978 said:

Dimensions are 4L x 3W x 5H
would need ~72 CFM rated fan to move the air out of it every minute I think...Whats the CFM calculation again?

Also I did think of an AC unit but wouldnt that take up a ton of wattage, I want to reduce that as much as possible.

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I beleive its 4L x 3W = 12sqft 12 x 5 = 60 cubic feet, im not sure but i think thats it, so your fan would be perfect, but also you need a fan to suck through ur hood and out your grow room to get rid of the heat! so another 76cfm should work!

DankJWeeks said:

I beleive its 4L x 3W = 12sqft 12 x 5 = 60 cubic feet, im not sure but i think thats it, so your fan would be perfect, but also you need a fan to suck through ur hood and out your grow room to get rid of the heat! so another 76cfm should work!

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if you can cut a hole into the roof and suck the hot air out and up to make sure that you keep fresh cool air in the closet and its an easy fix when you move

rickjames818 said:

if you can cut a hole into the roof and suck the hot air out and up to make sure that you keep fresh cool air in the closet and its an easy fix when you move

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its a good idea to cool the hoods too rickjames, cool the hood and also cool your room! im running ducting from the bottom of the tent through the hood and out the tent, then im using a booster fan and sucking at the very top of the tent

DankJWeeks said:

I beleive its 4L x 3W = 12sqft 12 x 5 = 60 cubic feet, im not sure but i think thats it, so your fan would be perfect, but also you need a fan to suck through ur hood and out your grow room to get rid of the heat! so another 76cfm should work!

Click to expand...

rickjames818 said:

if you can cut a hole into the roof and suck the hot air out and up to make sure that you keep fresh cool air in the closet and its an easy fix when you move

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Awesome, thanks for the information guys, you rock!

So what I am going to do is get a fan to suck the heat directly off the lights out of the box. I'll have a second general exhaust that takes any other remaining hot air out the top of the box where all the heat is rising and getting trapped.

The one thing I don't understand is that I am using CFL's + T5 but apparently they still get hot *sigh* I could just put my HPS back in there lol...damn i have to perfect this thing !

DankJWeeks said:

its a good idea to cool the hoods too rickjames, cool the hood and also cool your room! im running ducting from the bottom of the tent through the hood and out the tent, then im using a booster fan and sucking at the very top of the tent

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One problem is I have some home-made CFL hood/reflector that I made myself. Its a big piece of sheet metal that I bent in segments. Should I just abandon that and go with the CFL's hanging alone? The box is completely lined with Mylar so that should do enough reflection.

yep hang it by its self so the heat can rise off of them reflectors hold heat under them just just as well as they do light and when you take it off you will be able to get your lights closer to put some water or milk jugs in the freezer and throw them in when i starts getting to warm

Ya i would take that sheet metal off asap! guarantee you'll notice a difference and rickjames is right you would even beable to drop your cfls down a bit, hope it helps, post your result

DankJWeeks said:

Ya i would take that sheet metal off asap! guarantee you'll notice a difference and rickjames is right you would even beable to drop your cfls down a bit, hope it helps, post your result

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Excellent, I'm removing the damn sheet metal now. Then I'll take temp readings all around and let you guys know how much it changed.