150W HPS Grow Box - Construction...

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HIGHdration

Member


These are the designs for the grow box I plan to make.

Do you think that the computer fan is strong enough for the exhaust?

Any idea how to make a light trap?

Also, is there any improvements I should make before I begin construction?

Thanks, any help and advice is appreciated.
 
ow.douglas

ow.douglas

Well-Known Member
I have a 2x2 box, let me tell you what I have learned. You have 4 plants in the pix, I found 2 max, 1 ideal. Mine is 4' tall and I would go 5' if I had to do it again. I run T5 in mine and am able to keep the light 2" from the top of the plants and have slits at the top for the cables that the fixture hangs from. This allows me to get the lamp right up the ceiling of the box. I don't think that you will be able to do either w/150W HPS. Will that little axial fan run a carbon filter? I have never tried it but, I doubt it. Just one mans opinion, take it for what it's worth and good luck!
 
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HIGHdration

Member
The lights going to be hung vertically, so it would be a waste if all the light was not used, which is why I picked 4 plants. Also, the fan has 80 CFM rating, so hopefully it will work. Thank you for the input. I'm trying to get some opinions before I dedicate money to building it.
 
ExDex1x1

ExDex1x1

Active Member
HIGHdration said:
The lights going to be hung vertically, so it would be a waste if all the light was not used, which is why I picked 4 plants. Also, the fan has 80 CFM rating, so hopefully it will work. Thank you for the input. I'm trying to get some opinions before I dedicate money to building it.
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You don't need 4 plants to utilize all your light, just train your plants into a small SCRoG and force them to grow around the sides of the box, 4 plants is going to be way too crowded for that space.

Also 80 CFM is assuming there's nothing blocking the fan from pulling air, like say a carbon filter. 80CFM refers to the amount of air displaced when the fan is running literally on its own, on a table, in a lab, with normalized air pressure, at sea level, at average temp and humidity.

You want a stronger fan especially if you're using passive instead of forced intakes since 1 80CFM fan is not going to be able to produce enough negative pressure inside of your box to prevent air from leaking out of your passive intakes.

Also, you don't want that 2nd fan pointing down from the top of your box, if your intakes are at the bottom and exhaust is at the top, you're going to be blowing air against the natural flow you're trying to create with a passive intake and low CFM exhaust like this. You want to put the fan at the bottom, and most likely more than 1 so you can get decent airflow to all of your inner foliage to prevent mold and all those fun things that can happen with lack of ventilation.
 
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HIGHdration

Member
ExDex1x1 said:
You don't need 4 plants to utilize all your light, just train your plants into a small SCRoG and force them to grow around the sides of the box, 4 plants is going to be way too crowded for that space.

Also 80 CFM is assuming there's nothing blocking the fan from pulling air, like say a carbon filter. 80CFM refers to the amount of air displaced when the fan is running literally on its own, on a table, in a lab, with normalized air pressure, at sea level, at average temp and humidity.

You want a stronger fan especially if you're using passive instead of forced intakes since 1 80CFM fan is not going to be able to produce enough negative pressure inside of your box to prevent air from leaking out of your passive intakes.

Also, you don't want that 2nd fan pointing down from the top of your box, if your intakes are at the bottom and exhaust is at the top, you're going to be blowing air against the natural flow you're trying to create with a passive intake and low CFM exhaust like this. You want to put the fan at the bottom, and most likely more than 1 so you can get decent airflow to all of your inner foliage to prevent mold and all those fun things that can happen with lack of ventilation.
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Yeah, the fans not going to cut it. Do you have any recommendations for one that is strong enough that's not to expensive. Also, I plan to put the fan at the top below the light pointing upward. So I should use 1 or 2 plants with a circular screen around the light and train it?

Here's what the box will look like in 3D.
 
ExDex1x1

ExDex1x1

Active Member
As far as fans go, I'm assuming you want to stick with small PC fans. As far as I know Scythe has the strongest fan on the market right now (disregarding those obnoxious 250mm fans that NZXT makes because well, theyre obnoxious.) http://www.newegg.com/Product/Product.aspx?Item=N82E16835185054 They say 133 CFM in reality its a little less than that but its still a lot stronger than an 80cfm. It'd probably be your best bet for pulling through a carbon filter.

If you hang your light direct down from the middle of the box, a circular screen and training around the light would be your best bet for highest gram per watt per sqft in such a small place. You're going to want to make sure you keep the SCRoG as close to the walls of the box as possible so you aren't getting too close to the light.
 
H

HIGHdration

Member
ExDex1x1 said:
As far as fans go, I'm assuming you want to stick with small PC fans. As far as I know Scythe has the strongest fan on the market right now (disregarding those obnoxious 250mm fans that NZXT makes because well, theyre obnoxious.) http://www.newegg.com/Product/Product.aspx?Item=N82E16835185054 They say 133 CFM in reality its a little less than that but its still a lot stronger than an 80cfm. It'd probably be your best bet for pulling through a carbon filter.

If you hang your light direct down from the middle of the box, a circular screen and training around the light would be your best bet for highest gram per watt per sqft in such a small place. You're going to want to make sure you keep the SCRoG as close to the walls of the box as possible so you aren't getting too close to the light.
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I read this thread about PC fans and such and how they need a high pressure rating to pull through a scrubber. https://www.icmag.com/ic/showthread.php?t=131842

Then I found this fan... http://www.sidewindercomputers.com/deaf12recgrh.html

Do you think it's strong enough and give the box good ventilation?
 
bohicular

bohicular

Active Member
I wouldn't rely on a PC fan for that cooling, either. I ran a 150w hps in an enclosed cool tube with 2 pc fans in front of and behind the bulb, and it wasn't really enough (unless you live in a cold climate). If you're dead set on spending less than $30, you can get 6" duct booster fans, which would be better. I'd try to find a way to enclose that bulb.
 
Pullin' weeds

Pullin' weeds

Well-Known Member
I run 150s in my cab. I had to step up to a small bathroom fan as it was just getting too hot.
150s work well if you can maintain an fairly even canopy among your plants. Training and topping are key on a small grow
 
Guerillia Farmer

Guerillia Farmer

Well-Known Member
you can always go to a second hand/thrift shop and grab some used fans there..... they cheap as fuck like 2-5 bucks lol thats what i got 5 of them for like 10 bucks what a steal
 
crusty420

crusty420

Active Member
I run a 150W HPS my box is 3ft tall x 3ft wide x 2ft deep. I have 2 120MM cpu (45CFM) fan bringing in outside cool air. 2 120MM taking out the hot air. A 3 inch duct fan. And a full size oscillating fan blowing cool air on the light. And my temps still hit 86. I don't have a carbon filter either.
 
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