Building a 4x4x4 grow box

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AmateurAspirations

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Hi everyone! I have begun construction of a 4'x4'x4' grow box that is to be placed on a platform in a loft. The ceiling height on this platform is only 55" high but it provides a place for the operation to be concealed, protected and
has 2 seperate electrical lines to the fuse box that are un-used.
The box is constructed out of 2x4's and plywood. I've covered the inerior with mylar. The light I will be using is only 400w and HPS. IF I have done my math right that is the exact sq ft that a 400w can properly light. Am I right?
I am planning to get my ventilation set up this week to finalize the box and begin vegetation. My funds are beginning to run low and I think I want to cut a corner right now and purchase a 4" C.A.P. inline centrifugal from DH. I'm having a hard time figuring the math right now. Will a 4" fan cover the 4x4 box adequately?
And also , a question for you growers who have already earned their stripes, how much does that mylar really help? I consider it to be expensive and I am wondering how many folks actually put it to use?
I will throw some pics up when i can figure out how to turn off geo tagging on my cell or find a camera laying around that i knw i can trust
 
Attics can get incredibly hot in the summer. I am guessing that you are going to have to provide A/C to your space, maybe even when the lights are out. A 4" centrifuge type fan will provide enough air exchange, but unless you are pulling cool air through the light, I doubt it will not keep the light cool.

A 400W is only good for 10 sq ft. max. A space that is 4 x 4 is going to require at least a 600W. You need a min of 5000 lumens per sq ft for flowering.
 
thanks for the reply THG. THere is a portable unit that I am going to use to keep temps low. It is not really an attic as the studio is a renovated school building. it actually has great access to large windows and if needed the HVAC system is right there as well.Te,p's are rising even now, but only a few degrees above room temp. I have a few oscillating fans to also boost circulation as well.
NO comments as to the usefulness of Mylar though eh? It didnt sound as though the mylar was enough to make up for the extra sq footage in your opinion THG. Thank you for your wisdom!
 
You can get away with a 400w, You might lose a little on the yield but thats it..Mylar is always nice, if its flat and no wrinkles, it could make things worse if it is bent/wrinkled.

I would only run two plants and train them.. What kind of intake are you running?
Didnt catch if it was air cooled hood either?
 
You will definitely want to do as much LST, supercropping, and fimming to keep them girls low under the light. I personally would go straight to scrog under a 4' ceiling to prevent them from getting too tall.

I personally don't like mylar just because it is a pain to put it up and keep it straight and clean. I like to use reflectix, which you can buy from Lowes Home Improvement. It works well and is sturdy, and it has an insulative value as well. If you want to save money on that and you have some good quality flat white paint, that works as good as anything else for reflecting light.

I normally give DH a thumbs up but their prices have crept up lately. check on EBAY for the blowers, and other stuff. there are some really good deals on decent stuff. :) Good luck with it. keep us in the loop. get some pics up when you get them going. :)
 
Might be enough space to flower a few low ryders or some other autos.
 
A 400W is going to give unsatisfactory results IMO. Reflective film cannot make up for being underlit. A light mover helps, but I think they are a big PITA (I have 2 that I am going to be selling). You should use mylar, panda film, or flat white paint in all spaces. Your lighting is your most important part of the equation and closely linked to your yield. I really really am going to encourage you to make your space smaller, get another 400W, or get a 600W. Being underlit can result in light airy bud and a lot of stretch--something you will not have headroom for--4' of height can be a challenge in itself, even with a totally dialed in space.
 
yeah I agree a 400 isnt going to be happy Harvest...I ran mylar for a couple years but found it to be messy and expensive...Flat white paint works best and at 8 dollars a gallon..freshly painted walls every season...mojo for your grow

take care and be safe
 
hi guys! I appreciate all the feedback! Due to the heat concerns Ive changed the dimensionsand location of the box. The original plan was to do a lot of training on the plants or get my hands on auto seed..... but im concernedwith the quality.
So, the newbox is going to run 89 x 23 1/2 x 48". thats almost 7' of headroom in sacrifice for teh width...sound better???
The mylar is straight and not crinkled. that shirtes a pita in itself lol.next time flat white paint is the way to go.
pointers? ready... GO! :)
 
Sounds a lot better! That change gives you adequate light and adequate headroom to do a nice grow. Make sure you can keep your temps in line and go with it.
 
it's almost done! I have to hang the light and put one more panel in...... andit's finally done! I'm excited :)
 
4 foot tall will really limit everything. After root space and hood space, not to mention the distance from lights..your seeing plants that are 1-2 feet tall at the end of flower.
 
As hushpuppy said, i would scrog 1 maybe 2 girls immediately in conjuction with lst/top/fim. T5's for veg would keep your temps down. That 400 watt is going to need some good cooling too, AC would be ideal.
 
The box is built . Redesigned and modified. All while using the same materials. I constructed the walls using 4'X2' panels which I wrapped in Mylar. Lots of Duct tape, nails & screws, silicone caulk, weather stripping (to seal light on the roof and corners) and some L brackets. are all I needed. The box alone only cost me $100. :) .I'm going to have pics as soon as I figure out how.
 
Finally done.

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