400watts, 29"x24"x60" growbox questions

Code420 · #1 06-25-2008, 12:24 AM

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 · #2 06-25-2008, 12:31 AM

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 · #3 06-25-2008, 04:18 PM

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?

P@ssw0rd · #4 06-25-2008, 04:31 PM

Think centrifugal or aquirrel cage for fans

alti117 · #5 06-25-2008, 04:44 PM

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.

DfyAnt · #6 06-25-2008, 04:44 PM

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 · #7 06-25-2008, 04:57 PM

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.

Code420 · #8 06-25-2008, 05:22 PM

Quote:

Originally Posted by DfyAnt

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.

so the fan I posted made into one of these could even be some what of over kill? Easy to Build DIY Carbon Filter

ceestyle · #9 06-25-2008, 05:26 PM

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 · #10 06-25-2008, 05:54 PM

Quote:

Originally Posted by ceestyle

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.

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.