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Offlineyellownotepad
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Registered: 06/22/08
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is 400 watts too much for the space i am using?
    #74578 - 07/07/08 05:14 AM (8 years, 5 months ago)

right now i'm just vegging one plant in a box with CFL, but i want to step things up.  i have a 2'x2' ebb/flow setup and a 400w hps light.  i may still go with soil, but my main concern is whether this is too much heat for my closet. 

the space is about 6 feet high (the ceiling is about 8ft, but theres a shelf), 8 feet wide, and about 32" deep (these are rough measurements).  i'm going to section off half of the closet (it has sliding doors, i want to use the width of half the closet.  i'm thinking to build a freestanding box within the closet to contain air (so i can scrub it easily) and keep light from leaking out.  that leaves me with about 4ftW x 6ftH x 2'8" deep.  10.7sq feet floor space, 64.2 cubic feet of airspace. 

i'm willing to use cfl / fluoros if i have no other choice, but if i dont need a crazy venting system to use my HPS that i already own that would be great.  sorry for the rambling post.


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OfflineHanky
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Re: is 400 watts too much for the space i am using? [Re: yellownotepad]
    #74589 - 07/07/08 06:10 AM (8 years, 5 months ago)

You want a minimum 50w per square foot of floor space, so a 400 is a bit under what you need.  Supplement with CFL's or get a 600.

I run 1000w in 15 square foot giving me 66w PSF.


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OfflineSirius
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Re: is 400 watts too much for the space i am using? [Re: yellownotepad]
    #74615 - 07/07/08 08:38 AM (8 years, 4 months ago)

Quote:

yellownotepad said:
but if i dont need a crazy venting system to use my HPS that i already own that would be great.  sorry for the rambling post.




You're going to need a ventilation system capable of extracting at least twice the volume of air in the grow room every minute in order to provide the plants with the air exchange they need, regardless of which lights you are using, so keep that in mind.


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OfflineHanky
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Re: is 400 watts too much for the space i am using? [Re: Sirius]
    #74617 - 07/07/08 09:23 AM (8 years, 4 months ago)

Agreed.

I'm of the opinion that ventilation is one of the most important and most often overlooked areas of growing.

I've got three exhaust fans one intake fan and two circulating fans in my room.    Air is key.


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Offlineyellownotepad
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Re: is 400 watts too much for the space i am using? [Re: Sirius]
    #74741 - 07/07/08 02:03 PM (8 years, 4 months ago)

Quote:

Sirius said:
Quote:

yellownotepad said:
but if i dont need a crazy venting system to use my HPS that i already own that would be great.  sorry for the rambling post.




You're going to need a ventilation system capable of extracting at least twice the volume of air in the grow room every minute in order to provide the plants with the air exchange they need, regardless of which lights you are using, so keep that in mind.




so it is in my best interest to be selective about how tall i make my box?  if the plants do not occupy the full space, i am confused how the rule would still apply.  i.e. same size plants in a 10 cubic foot space or a 20 cubic foot space, they consume the same amount of air regardless...


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Offlineyellownotepad
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Re: is 400 watts too much for the space i am using? [Re: yellownotepad]
    #74746 - 07/07/08 02:10 PM (8 years, 4 months ago)

another thing - i'm looking at 80mm computer case fans that claim 30-35cfm.  does this mean that even with the space i listed, 2 or at most 3 fans for each side of the ventilation system would accomplish 2+ air exchanges per minute?


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Invisiblecoda


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Re: is 400 watts too much for the space i am using? [Re: yellownotepad]
    #74895 - 07/07/08 04:17 PM (8 years, 4 months ago)

Quote:

i.e. same size plants in a 10 cubic foot space or a 20 cubic foot space, they consume the same amount of air regardless...




yes, that's true, however the rest of the air will become stale and heat will most likely build up if you don't have enough power from your fan to move it.  Having extra vertical room is good because it allows you extra space to grow up in.  If you plan on keeping your plants at a certain height you don't need 9 ft of extra space.  Always allow yourself a little wiggle room as well, it's best to have extra just in case.


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Offlineyellownotepad
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Re: is 400 watts too much for the space i am using? [Re: coda]
    #75548 - 07/08/08 02:11 AM (8 years, 4 months ago)

good point.  what kind of height should i guesstimate for?


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OfflineSirius
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Re: is 400 watts too much for the space i am using? [Re: yellownotepad]
    #75704 - 07/08/08 05:16 AM (8 years, 4 months ago)

I'd think you'd want to have at least six feet of height. You might be looking at an average of three foot tall plants, and when you factor in the height of the pots, the distance the light will need to be from the canopy, as well as the size of the reflector for the light itself, you'd be needing about that much space. Personally, I would use as much height as I'd be capable of using. This leaves room to adjust in case plants need more height or you intend on growing sativa dominant strains (a great idea :hehehe:), and extra height should only help with keeping heat away from plants and especially the roots.

Regarding your earlier questions, it might make sense that a bigger room might not need as much ventilation as a smaller room for the same size plants, but I think it would still be important to keep that level of air movement occurring to help keep fresh CO2 where the plants need it at all times. With the volume you mentioned, that many of those computer fans would certainly do the trick, but since you are planning on using a carbon filter, I don't think that computer fans would be too effective in pulling air through it (not to mention that I'm not sure how you could even rig that up). Maybe you could keep the fans pulling air in through the intake, and get an inline extractor fan for the exhaust, pulling air through the carbon filter? You'd be looking at around $100 or so for one, but its the most effective way of handling the situation. I picked up one with 214cfm for about $150 and after getting the cord hooked up and plugging it in, I was impressed with how quiet it is and how cool it is. :lol:


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InvisibleSRH
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Registered: 06/15/08
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Re: is 400 watts too much for the space i am using? [Re: Sirius]
    #82181 - 07/13/08 06:33 PM (8 years, 4 months ago)

you can use a 1000watt in a 2x2 space as long as the temp. stay around 75f.

depending how closed in the space is your gonna want at least a 4in vortex to cool down the light.

I use a 6x3x3 space with a 1000watt, A/C & vortex blower
temps are 65-75f


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Cannabis, Marijuana, Ganja & Greens >> Cannabis Cultivation

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