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Building a flowering box for 400w HPS

Q

QuantumFizz

New member
I got some materials today for building a box to accommodate 5 plants which have been vegging for 5 weeks. I got enough wood to build the box 6 feet tall, 2 feet wide, and 18 inches deep. Will a 400w HPS be enough for a box this size?

I'll put an intake an exhaust fan and two oscillating fans, one pointed at the bulb. I might make a cool tube if heat is an issue but I'm not planning for that yet.

I appreciate any comments, I'll be happy to post photos as I'm building the box if there's interest.
 
Jnugg

Jnugg

Active member
Veteran
I don't think that would be a good idea.


2' x 1.5' = 3 square feet

400w / 3 sq. feet = 133w per square foot.

50,000 lumens / 3 sq. feet = 16,666 lumens per square foot.

That would be an f'ing nightmare to keep cool and I don't see that much light helping you.

In that size space I would do a 250w HPS.

250w / 3 = 83w per sq. foot

28,500 lumens / 3 = 9,500 lumens per square foot.

Cannabis in it seedling or rooting cutting form requires 375 lumens per square foot as a minimum.Cannabis in it's vegetative stage requires 2500 lumens per sq. foot (I like 5,000+) and in it's flowering stage 6000-7000 lumens per sq. foot as a minimum (I like 8,000-10,000) with 7,000-10,000 being ideal.Any light intensity beyond this and you risk running into the realm of diminishing returns and bleaching and burning of your plants.

I'd go with a 250w HPS in that area,or make the box/cab a little bigger like 2' x 2.5' or 2' x 3' (w x l obviously),then you can get away with a 400w HPS.
 
B

BLUNToPOTomuss

Member
I got 5.6 zippers outta 3 6'' clones no veg, straight 12's with age old bloom and grow only on my first try in my 2x2x4 cab with a 400 hps.

I say go with the 400 and make it work for the stanely blower fan.

I saw at Walfart her too stanely blowers anre going for $12.99 untill the end of the "season", whenever that is....

Ive got 4 plants going now Lemon Train Wreck, Skunk#1, Afgoo, and Shiva Skunk Berry.

Gunna cram 6 in there with 2.5 gallon pots after harvest. looking at the 8th
 
FRANKENBLUNT420

FRANKENBLUNT420

me blunt is like, wicked yo!! owight
well i would go with the 250 opinion as well, but if you have more wood than you have money to buy another light, then just make the cab bigger.

and 3sq. feet for 5 plants seems a lil cramped IMO.

build a bigger box, go hard or go home
 
Q

QuantumFizz

New member
what if I increased the size of the box to 4' feet? So that would be 6' high, 4' wide, and 18" deep. I already have a 400w and want to avoid getting another HID, I don't mind adjusting the size of the box.
 
B

BLUNToPOTomuss

Member
I think that would be a GREAT idea for the 400. If you can cool it use the 400.! I wish I made my cab atleast 5' tall! and Id recomend that height minimum i you are going to use the 400, I wish I did!! I need the space as will you Im sure with that 400!
 
Q

QuantumFizz

New member
BLUNToPOTomuss said:
I think that would be a GREAT idea for the 400. If you can cool it use the 400.! I wish I made my cab atleast 5' tall! and Id recomend that height minimum i you are going to use the 400, I wish I did!! I need the space as will you Im sure with that 400!
Click to expand...

great, thanks for the feedback. I'm wondering if a cool tube will be necessary here, I'm looking for a DIY reflector that I can put an exhaust fan on the end of.
 
Jnugg

Jnugg

Active member
Veteran
QuantumFizz said:
great, thanks for the feedback. I'm wondering if a cool tube will be necessary here, I'm looking for a DIY reflector that I can put an exhaust fan on the end of.
Click to expand...


4' x 18" will not work either as the light simply won't reach out 4' in either direction (left,right,fron,back,or down!)

Make it either 2' x 2' absolute minimum or 2' x 2.5' or 2' x 3'

2 x 2 = 4 400w 50,000 lumens / 4 sq. feet = 100w per sq. foot and 12,500 lumens per sq. foot.A bit much if you ask me but with serious ventilation of the box/cab and air-cooling of the light you should be able to manage,as long as ambient temps are in check or can be kept in check,but keep a watch out for bleaching and light burn.

2 x 2.5 = 5 400w 50,000 lumens / 5 = 80w per sq. foot and 10,000 lumens per sq. foot.With proper ventilation and air-cooling this would be option 1.


2 x 3 = 6 400w 50,000 lumens / 6 sq. feet = 66w per sq. foot and 8333 lumens per sq. foot.With proper ventilation and air-cooling this is option #2.


So there you have it.Either stick with the size cab you want which is 2' x 18" and use a 250w HPS or a 270w HPS......or......make the cab bigger (2' x 2' or 2' x 2.5' or 2' x 3') and use a 400w HPS.*NOTE* 250w/270w HPS can be used in 2' x 2' grow space as well.


Oh,and yes a cooltube would help but an air-cooled reflector will work too...the tough one is finding one that will fit a 2' x 1.5' or 2' x 2' area.
 
Q

QuantumFizz

New member
damn, thank you for all your calculations.

If 18" depth is unacceptable for a 400w HID then I'll find a different location for the big to make it larger. If you could make a box any size for a 400w flowering chamber what size would you pick?
 
Q

qbert

Member
QuantumFizz said:
damn, thank you for all your calculations.

If 18" depth is unacceptable for a 400w HID then I'll find a different location for the big to make it larger. If you could make a box any size for a 400w flowering chamber what size would you pick?
Click to expand...


I picked right about 2' x 3'. Its a tad bigger to accommodate fans and misc stuff on the ends and might grow a tad deeper if I can figure any way to turn my reflector and squeeze it in there perpendicular to the length of box. Oh and this box is planning to supplement the 400w hps with 110w of 6500k pl-l's. So, I'm actually a bit higher wattage. I went overboard with ventilation. Have yet to see if it will be enough to keep temps down, but I'm betting it will.
 
B

BLUNToPOTomuss

Member
I wish i made my cab 2x3x5! the extra foot both ways would allow me to veg for a week! as of now I can only go straight 12's from clones if I dont want to tie the girls down. IF ONLY I HAD THAT EXTRA FOOT OF HIEGHT!!!!

Jnugg makes some good points! I am able to run my 400 at 100w psqft and 12000 lumens without light bleaching or heat probs, but like he said It takes a good grasp of how ventilation and air flow works to get a cab this small to stay cool.

It is possible but definately easier to cool if you go with a 2x3x5, and with the additional foot of hieght you will not be disappointed!!!

Good Luck!
 
odin_

odin_

Member
i once grew with a 600 in a 2x3 lol

i got the most awesome colas, but the overall yield left something to desire lolol
 
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