I have a 3x4 area. In general how much area can a 400w mh cover for veg? I was thinking 3x3. My exhaust is in the back left (at the top). I'm using a 4" elicent for exhaust and plan on cutting some intakes but not sure where. Originally i had planned on cutting 5 or 6 2"-3" holes across the bottom right. Now i'm thinking 2 4" holes in the bottom right corner. What do you guys think?
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Metal Halide & Intake ?
- Thread starter Ninja420
- Start date
3' x 3' or 3' x 4'
As for light requirements for plants...According to Indoor Marijuana Horticulture :The Indoor Bible by Jorge Cervantes,Cannabis as a seedling only needs 375 lumens per square foot.As a clone only 375 lpsf are needed.In vegetative stage of their life,cannabis needs 2500 lpsf,in flowering stage 10,000 lpsf is what you want to aim for if you want big juicy nugs but 7500 lpsf is acceptable.
In a 3' x 3' area = 9' squared lit by a 400w MH bulb that produces 36,000 initial lumens will give you 44.44 wpsf and 4000 lpsf.....deffinately acceptable.
As far as intakes I see you said you'll be using a 4" 170cfm elicent and want to use passive intakes (good idea).You want your intake area to be atleast 3.3x larger than the inlet on the exhuast fan.So if you have a 4 inche inlet on the exhuast fan then you would want eight 2" o.d. PVC pipe with 90 degree PVC elbows to block/trap light from entering/escaping the grow,or one 8" x 8" darkroom louver vent.
Checkout the Ventilation 101 link in my sig.
As for light requirements for plants...According to Indoor Marijuana Horticulture :The Indoor Bible by Jorge Cervantes,Cannabis as a seedling only needs 375 lumens per square foot.As a clone only 375 lpsf are needed.In vegetative stage of their life,cannabis needs 2500 lpsf,in flowering stage 10,000 lpsf is what you want to aim for if you want big juicy nugs but 7500 lpsf is acceptable.
In a 3' x 3' area = 9' squared lit by a 400w MH bulb that produces 36,000 initial lumens will give you 44.44 wpsf and 4000 lpsf.....deffinately acceptable.
As far as intakes I see you said you'll be using a 4" 170cfm elicent and want to use passive intakes (good idea).You want your intake area to be atleast 3.3x larger than the inlet on the exhuast fan.So if you have a 4 inche inlet on the exhuast fan then you would want eight 2" o.d. PVC pipe with 90 degree PVC elbows to block/trap light from entering/escaping the grow,or one 8" x 8" darkroom louver vent.
Checkout the Ventilation 101 link in my sig.
A 400 would be better suited to a 2x3 grow. 3x3 is stretching it thin. Start with 2X intakes and see where that gets you. Some here swear by 4X. Get intakes as low as you can without airflow being blocked by pots or res.
Oh yeah Ventilation 101 rocks. It may tax your brain cells (does mine) but, it's something that you can't read enough.
Oh yeah Ventilation 101 rocks. It may tax your brain cells (does mine) but, it's something that you can't read enough.
A 3x3 allows LESS space to work in. The more space you use up, the less space you have to work in. In a 3x3 tent a 3x3 grow allows no space at all. In a 4x4, 3x3 would let you in, barely; 2x3 would give you space to work.
Note lamps throw no light forward or back. As a result, the effective footprint is more rectangular than square. By placing lamp perpendicular to the length of the grow, we can lower the lamp AND increase footprint at the same time.
Note lamps throw no light forward or back. As a result, the effective footprint is more rectangular than square. By placing lamp perpendicular to the length of the grow, we can lower the lamp AND increase footprint at the same time.
