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Thread: First Timer 4x4 DIY

  1. #1
    420 Member Lard Bernard's Avatar
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    First Timer 4x4 DIY

    I am a first time grower in the southeast us. I am a contractor so getting materials and general knowledge of how to engineer things together and making it work is what i do for a living so i have had a little fun prepping for this. i am starting out with a 4x4 grow box made out of OSB. i am going to start 4 plants with a 150w MH and 8 cfls (only 4 in the pic). i am also waiting on my HTG order with 600 w HPS for flower and reflective mylar and foxfarm nutes. i am using fox farm ocean for medium.

    i want to master lst to maximize my space in this box. i have some lighting questions. keeping that in mind should i keep all of the lights over head or is having the cfl's on the sides as pictured a better method? Also should i hang the MH so it will be closer to the plants and raise it as needed? When should i start flowering in a 4' space?

    also the grow space is in an attic and temperatures are going to be an issue. it is really cold there now and will be really hot in the summer. i have a small 1500w space heater that works ok but i would rather not use it because of the energy consumption. but i think i am going to have to at least until the 600w hps is putting out enough heat on its own. i was thinking of insulating the roof to keep the heat out in the summer but i dont think it would really help that much in the winter. the 600w light has an air cooled hood and i will be venting that outside in the summer but any temperature suggestions that are affordable would be much appreciated. i have already ran a dedicated 20a circuit up to the space so thats not a really big issue. i figure about 2000w per 20a breaker is acceptable. i just hope i dont have to run the heater and 600w hps at the same time.

    any questions, tips, or advice would be very much appreciated.






  2. #2
    Member of the Month 3rd Place Winner (Dec 09') Screwnuts33's Avatar
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    Re: First Timer 4x4 DIY

    Looking good. You will want to seal up the seems so you don't have light leaks. I would use your CFL's as side lights. Lower your MH light to about 18" above your seedlings.

    If you plan to LST you can veg a little longer. Keep in mind when you go to flower (12/12) your plants will at least double in height. Allow headroom for your light and height for you pots.

    I am also growing in my attic. Temps were fine when I started then I had to add some heat. During veg was fine as I ran my lights 24/0. When I switched to flower I had to add heat during the lights out cycle. Not a chance I will be able to grow in the attic during summer.

    20a breaker is not enough for 2000 watts. You are pushing the max which is never a good idea with electricity. Go up to 10ga wire and a 30a breaker to be safe.

  3. #3
    420 Member Lard Bernard's Avatar
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    Re: First Timer 4x4 DIY

    i will just add another 20a circuit or tie into the existing 20a circuit that is in the garage that is very sparingly used if i get in a situation where i am running too much electricity on one circuit. having the heater run during lights off shouldnt be a problem.

    i am going to seal everything up. i have weather stripping running down the side of the door and i am going to put a rubber threshold or something on the bottom. everywhere else i am just going to use spray foam.

  4. #4
    Member of the Month 3rd Place Winner (Dec 09') Screwnuts33's Avatar
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    Re: First Timer 4x4 DIY

    Be careful using glues, caulk, and spray foam. The off gassing of some products can kill your plants. Seedlings are especially vulnerable.

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    420 Member mcrog's Avatar
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    Re: First Timer 4x4 DIY

    Thanks for the feedback Screw. I'll be helping Dhrone on this grow. What would you use to seal up the seems?

  6. #6
    Member of the Month 3rd Place Winner (Dec 09') Screwnuts33's Avatar
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    Re: First Timer 4x4 DIY

    I would use a latex caulk and allow plenty of drying time before any plants go in.

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    420 Member Lard Bernard's Avatar
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    Re: First Timer 4x4 DIY

    Quote Originally Posted by Screwnuts33 View Post
    I would use a latex caulk and allow plenty of drying time before any plants go in.
    after the spray foam dries it should be fine right?

    Also, how important do you guys think it is to sterilize the soil/medium? i knew nothing of it until last night.

  8. #8
    420 Member Lil Neutrino's Avatar
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    Re: First Timer 4x4 DIY

    Screw pretty much hit on the major issues...

    I used an outdoor latex caulk on my cabinet to seal along the seams and didn't have any troubles...as screw mentioned just let it cure before using it. Same with the expanding foam...silicon too...the toxic fumes are given off during curing so any time after that should be good.

    I don't have a lot of experience growing but my first four plants did just fine using premixed soil (Fox Farm Ocean Forest)...I imagine they sterilize it before they add their nutes to it though so I didn't bother. If you're using bulk soil from a gardening store (i.e., shovel it in to your truck bed to haul) or from soil you dug up yourself it could be worth pursuing.

    Oh...and 2000W on a 20A circuit is 16A at 120VAC. That is 80% of the rated capacity of the breaker which is in all practicality on the very very edge of being usable. I would also agree that upgrading to a 30A CB with appropriate wiring is your best bet. As far as tapping off the garage circuit even though it is used sparingly I wouldn't chance it especially in the summer where your ambient air temp will be pushing the upper limits of the calculations used in the NEC to determine conductor ampacity ratings for that application in those temps (NEC sizing charts use 86F and 104F as typical ambient air temps when rating cables). After living in the Deep South for over ten years I am safe in saying that 86F is a cool day in June much less the hotter months lol. If you need time to save up some money for the larger breaker and wire you could use the other circuit but I would recommend changing it out before it gets too warm outside.

    Regarding temperature in the attic...yes, it's going to be a big problem unless you can pipe in cooler air. What room is below the cabinet? Any chance you could install an intake duct through the roof in to the cabinet to pull cool house air in? If you have a central heating/air conditioning system you could even disguise it to look like an A/C vent in the ceiling with some excuse as to why it never works Just remember no matter how much air flow you have the air will never be cooler than ambient so if it's 95F in your attic that's the coolest temps your plants will see without a cooler air source. I have seen pics of people using portable A/C units or even window units to help cool grow rooms. Not exactly an economical alternative but if your hands are tied it is an option. Other than those two ideas I can't think of anything else off the top of my head.

    I would also recommend a door that swings open left/right rather than up/down as it will be easier to seal the light leaks...and anywhere light leaks out smell can leak out too. Sealing a door can be a PITA as I learned but with a little forethought and experimentation it can be solved. I have decided that for my personal cabinet having a wide lip around the edge of the cabinet frame where the door meets will be the easiest along with some wide but thin rubber weatherstrip (rubber lasts longer than foam, especially with constant use like grow cabinet doors get) and latches.

    The CFL's aren't going to do a whole lot if you're going to be using HO lights since they penetrate so much better and have much higher lumen output. On other hand the more the merrier, right? :D I too would mount them on the sides but the thing with CFL's is that since they are fluorescents they do not do a very good job of getting those photons to the plants unless they are very close. Fortunately they run amazingly cool and you can usually put them within 2" of a plant without burning it. Depending on how many plants you have eight bulbs may not be enough to be worth the hassle of wiring up and mounting.
    Last edited by Lil Neutrino; 01-09-2010 at 01:04 AM. Reason: more info

  9. #9
    420 Member Lil Neutrino's Avatar
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    Re: First Timer 4x4 DIY

    Just saw where you were contemplating insulating the roof...I say do it. In the summer it is a guarantee that your attic air temp will be too high. In the winter your HO lighting should keep the temps up in the cabinet, you could even experiment with speed controllers on the exhaust fan to move a little less air and keep the temps a bit higher if you find them too low in the winter (highly doubtful).

    To put the winter thing in perspective I was using 12 26W CFL's in my 32ft^3 cabinet (4'W X 4'H X 2'D) which is in my bedroom. The amount of heat produce by those bulbs was enough to have a noticeable rise in the air temp in my bedroom...enough that I often found myself getting up once a night to bump the A/C on but I can't stand being too warm when I am sleeping. Even my gf commented on how much warmer the lights made it so I wasn't imagining things ha!

  10. #10
    420 Member Lard Bernard's Avatar
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    Re: First Timer 4x4 DIY

    Quote Originally Posted by Lil Neutrino View Post
    Screw pretty much hit on the major issues...

    I used an outdoor latex caulk on my cabinet to seal along the seams and didn't have any troubles...as screw mentioned just let it cure before using it. Same with the expanding foam...silicon too...the toxic fumes are given off during curing so any time after that should be good.

    I don't have a lot of experience growing but my first four plants did just fine using premixed soil (Fox Farm Ocean Forest)...I imagine they sterilize it before they add their nutes to it though so I didn't bother. If you're using bulk soil from a gardening store (i.e., shovel it in to your truck bed to haul) or from soil you dug up yourself it could be worth pursuing.

    Oh...and 2000W on a 20A circuit is 16A at 120VAC. That is 80% of the rated capacity of the breaker which is in all practicality on the very very edge of being usable. I would also agree that upgrading to a 30A CB with appropriate wiring is your best bet. As far as tapping off the garage circuit even though it is used sparingly I wouldn't chance it especially in the summer where your ambient air temp will be pushing the upper limits of the calculations used in the NEC to determine conductor ampacity ratings for that application in those temps (NEC sizing charts use 86F and 104F as typical ambient air temps when rating cables). After living in the Deep South for over ten years I am safe in saying that 86F is a cool day in June much less the hotter months lol. If you need time to save up some money for the larger breaker and wire you could use the other circuit but I would recommend changing it out before it gets too warm outside.

    Regarding temperature in the attic...yes, it's going to be a big problem unless you can pipe in cooler air. What room is below the cabinet? Any chance you could install an intake duct through the roof in to the cabinet to pull cool house air in? If you have a central heating/air conditioning system you could even disguise it to look like an A/C vent in the ceiling with some excuse as to why it never works Just remember no matter how much air flow you have the air will never be cooler than ambient so if it's 95F in your attic that's the coolest temps your plants will see without a cooler air source. I have seen pics of people using portable A/C units or even window units to help cool grow rooms. Not exactly an economical alternative but if your hands are tied it is an option. Other than those two ideas I can't think of anything else off the top of my head.

    I would also recommend a door that swings open left/right rather than up/down as it will be easier to seal the light leaks...and anywhere light leaks out smell can leak out too. Sealing a door can be a PITA as I learned but with a little forethought and experimentation it can be solved. I have decided that for my personal cabinet having a wide lip around the edge of the cabinet frame where the door meets will be the easiest along with some wide but thin rubber weatherstrip (rubber lasts longer than foam, especially with constant use like grow cabinet doors get) and latches.

    The CFL's aren't going to do a whole lot if you're going to be using HO lights since they penetrate so much better and have much higher lumen output. On other hand the more the merrier, right? :D I too would mount them on the sides but the thing with CFL's is that since they are fluorescents they do not do a very good job of getting those photons to the plants unless they are very close. Fortunately they run amazingly cool and you can usually put them within 2" of a plant without burning it. Depending on how many plants you have eight bulbs may not be enough to be worth the hassle of wiring up and mounting.
    thanks for the detailed reply man.

    i might end up running another circuit up there as it is pretty assessable. the panel is right below that attic space. this space is actually the attic for the detached garage. so tapping into the central a/c is going to be difficult to do. there is a tiny little opening that connects the two and i am going to need to get up there and check it out to see if it is doable. looks like i may need to just run some african/heat loving strainds during the summer months.

    i got the doors sealed off by putting a bottom threshold piece and wstripping and two side latches on either side. i thought about swinging the door from l to right but space is really limited and the hinges would eventually give way unless i bolted them through.

    i was considering in the colder months to only have a small intake fan blowing in and leaving the hole i made for the wires just open so that wil l be the exhaust for the box. the air in the attic right now is pretty cold so i dont want a lot of that in there. i also will probably have to think about a bigger heater for the attic as the tiny one i have is weak.

  11. #11
    420 Member Lil Neutrino's Avatar
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    Re: First Timer 4x4 DIY

    Quote Originally Posted by dhrone View Post
    thanks for the detailed reply man.

    i might end up running another circuit up there as it is pretty assessable. the panel is right below that attic space. this space is actually the attic for the detached garage. so tapping into the central a/c is going to be difficult to do. there is a tiny little opening that connects the two and i am going to need to get up there and check it out to see if it is doable. looks like i may need to just run some african/heat loving strainds during the summer months.
    You're welcome! I think I may have confused you about my ventilation idea. Rather than tap in to the A/C vents just run a vent through the floor of the attic in to the roof of the garage so that cooler air can be pulled in from there. Hot air rises so pull air in from as low as you can...even in your home there can be a 3-4F temp difference between the floor and eye level. I think what may have confused you was when I said you could cover the intake hole with a vent so that it looks like an actual A/C vent...it would just be nonworking (and be sure to block out any light from transmitting through it, that would be a lil suspicious lol).

    i got the doors sealed off by putting a bottom threshold piece and wstripping and two side latches on either side. i thought about swinging the door from l to right but space is really limited and the hinges would eventually give way unless i bolted them through.
    Good deal. I had to put casters on my cabinet door due to the weight of the door and it's size or, like you said, it would rip the hinges out of the wall.

    i was considering in the colder months to only have a small intake fan blowing in and leaving the hole i made for the wires just open so that wil l be the exhaust for the box. the air in the attic right now is pretty cold so i dont want a lot of that in there. i also will probably have to think about a bigger heater for the attic as the tiny one i have is weak.
    The air in that cabinet should heat up nicely with your high output lights running but I forgot that those lights have to turn off at some point unless you're running a 24/0 veg cycle...but depending where you live in the southeast those cooler winter temps shouldn't last too long. I would recommend an oil heater over something that blows hot air as that will really dry out the air and then you'll have a new issue with possibly trying to raise the humidity. Just a thought.

  12. #12
    420 Member Lard Bernard's Avatar
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    Re: First Timer 4x4 DIY

    oh ok that is actually a good idea. i think that air will be cooler and more consistent than intaking the air from outside like i originally planned.