400watts, 29"x24"x60" growbox questions

Code420

Code420

Well-Known Member
Well I've been planning on making a new grow box for flowering for a while now and today I bought a 400 watt hps for 120$ from a friend. This is the design I've thought up. My questions are these, would it be better to put the plywood on the inside or outside of the frame? What kind of exhaust fan would you guys recommend?. I'm thinking of picking this one up but It seems like it might make a lot of noise Inductor 8 In. In-Line Duct Booster Fan - DB208 at The Home Depot I'm planning on putting a fan in the exhaust and probably a smaller one blowing across the light. I will probably add a third one to blow against the actual plants. How is this set up looking? Will I most likely have a heat problem?
 
dr.greenthumb85

dr.greenthumb85

Well-Known Member
set up looks right but that booster fan isn't going to do it i don't think. while it will help circulate the air, i don't think it will have the cfm's you need to keep temps down.
 
Code420

Code420

Well-Known Member
How many cfms should I have? The space would be about 24 cubic feet total. Im starting to think its too tall for such a skinny area.

Also what would this set up be best for? I was originally going to do a sog with it but I'm starting to think it would work well with a scog. Plus with a scrog I could have far fewer plants which is always nice if you get busted and I have a lot of experience with lst which is somewhat similar. More importantly though, which would give me the better yield per square foot?
 
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A

alti117

Active Member
i have the same fan but in a 6" and it is very quiet, i would recomend one. im in the process of gorwing scrog style aswell and i think that in your limited space a scrog would be optimal, possibly even a Vscrog.
 
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DfyAnt

DfyAnt

Well-Known Member
2.4 x 2 x 5 = 24 / 5 = 4.8 cfm

5 is the number of minutes it would take to cool your area.
my grow tent is 4 x 4 x 6.5ft = 104 / 5 = 20.8

the smallest fan out there (4in) will work.
 
ceestyle

ceestyle

Well-Known Member
I hope you have a cooled hood rather than just a reflector. If not, you are going to cook. You will need to take all measures possible to cool that light, probably including moving the intake to right next to the light to help cool the bulb. If you need to go that route, I would seal off the upper cubby with the ballast in it. Put the ballast on insulating blocks - styrofoam, concrete, whatever - or suspend it from the ceiling to prevent conduction through the wood (yeah, it's a poor conductor, but it'll get hot). Once you've got that sealed, punch an 8" hole in it and run ducting from that hold to right next to the light fixture. This way you can direct your air flow and still have cooling air running over the ballast.

Other than that, I think it's a good design. It's unfortunate that you can't trade some of that vertical space for floor space. You could then run SOG or SCROG, both of which are best for minimizing use of vertical space at the expense of floor space.


As it is, I'd probably run 'em tight and go for one big cola on each ... like super SOG, essentially how you've drawn it in your figure.

The CFM calculation done in the post above is great for what your plants need air-wise, but if you run into a heat problem, you can use quite a bit more than that formula would recommend.
 
ceestyle

ceestyle

Well-Known Member
That fan is pretty weak, actually. It's not going to be overkill. It's rated at like 200+ CFM. It's cheap as hell anyway. Buy the damn thing, turn on your light, and see what kind of temps you get. Then go from there.
 
Code420

Code420

Well-Known Member
ceestyle said:
That fan is pretty weak, actually. It's not going to be overkill. It's rated at like 200+ CFM. It's cheap as hell anyway. Buy the damn thing, turn on your light, and see what kind of temps you get. Then go from there.
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I haven't built the box yet, I'm just getting some opinions and all the details together. Now that I'm looking at indifferent types of fans, duct fans seem REALLY weak for their price.
 
ceestyle

ceestyle

Well-Known Member
Code420 said:
I haven't built the box yet, I'm just getting some opinions and all the details together. Now that I'm looking at indifferent types of fans, duct fans seem REALLY weak for their price.
Click to expand...
well, they're really not meant to be the only source of air flow. They're meant to /boost/ airflow.

the reason people use them is because they're the only fans available at those kind of prices. i have one that works fine with my 400W cooltube.
 
Code420

Code420

Well-Known Member
potlike

potlike

Well-Known Member
Joker he will still have heat problems all that is doing is blowing around hot air...

buy the stanley blower fan and attach it to some ductwork that exhausts it outside your box...

you could buy a 5000 btu air conditioner to blow cold air in if you wish you can get those for $100 at Walmarts or $20-$60 at alot of pawn shops.

Joker was right in that you should have some air circulating for your plants though... helps promote good stem growth and stronger plants.


-potlike
 
kief13

kief13

Well-Known Member
um how u ganna hook up a filter to that blower?if it's your exhaust?and no don't take jokers advise,my input go with the 420cfm fan,if heat is a issue with it still either step it up a size or type of fan.
Or find a high cfm rated pc fan to help exhaust air.u can find a 50cfm one for like 8bucks on the net.and if u can house the ballast outside of box it would help,or maybe if not use one of them pc fans to help cool it nifty little fans in my opion
 
potlike

potlike

Well-Known Member
it's very simple kief you can get redirectors that size that go to standard 4 inch pvc OR use duct tape like I did. Google stanley blower fan mods there are several of them around. They aren't 2000cfm as advertised but still blow a hell of a lot air. I got mine from Walmart for $39.


-potlike
 
jorda

jorda

Active Member
Code .... I have a similar box I built.
First, I would use 2x2 for the frame on the inside.
Next, if you are set on the size you have which is roughly 2'x2' figure 4 plants max, maybe less.
Also, cooling is going to be a big factor as I had to move my box from the warm garage into the airconditioned house to get it at the proper temps when it was warm outside. It was either that or run another AC unit just for the box or only use it during the fall, winter and spring seasons.
I hope that helps!
 
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