Can somebody please check my math?

Putting together a grow closet. The "closet" is an IKEA wardrobe with interior dimensions of 22" deep, 36" wide, 6' tall. Before I pull the trigger on the bulb order, I wanted to make sure I had it about right:

42W CFLs, 6500K, 2800 lumens each.

Closet is 22x36 = 792 sq.inches = 5.5 sq.feet.

Shooting for 7500 lumens / sq.ft, so 5.5 x 7500 = 41250 lumens.

41250 lumens / 2800 lumens/bulb = about 15 bulbs

So fifteen 42W CFLs in a 2'x3' space? Yes? No? 630W total.

Went with 42W bulbs because higher wattages have few lumens per watt, and get expensive quickly. Would have needed 10 85-watt CFLs (850W total) to make the same number of lumens, and the bulbs cost twice as much!

Seems like a lot of bulbs, is all.

--Bud
 

stonesour

Well-Known Member
ive got 85 watt 2700K that are 5700 lumens each. im running 9 of them. 765 watts in 5 square feet. 51300 lumens divided by 5 = 10260 lumens per square feet. These bulbs are about the same lumens per watt than those 42 watt ones.
 
ive got 85 watt 2700K that are 5700 lumens each. im running 9 of them. 765 watts in 5 square feet. 51300 lumens divided by 5 = 10260 lumens per square feet. These bulbs are about the same lumens per watt than those 42 watt ones.
I'm having trouble finding high-wattage bulbs for vegging that have good lumens per watt. I've seen those 5700 lumen 85W bulbs for flowering; I'll probably go that way when the time comes, but for vegging I'm looking for 6500K bulbs.

--Bud
 

desertrat

Well-Known Member
this will help you for awhile - the 7500 lumens per square ft is the recommended amount of light for flowering. you only need half that for vegging.

also a 400 watt hps light will provide the same amount of light as your 15 cfl's with less energy and heat.
 

stonesour

Well-Known Member
I'm having trouble finding high-wattage bulbs for vegging that have good lumens per watt. I've seen those 5700 lumen 85W bulbs for flowering; I'll probably go that way when the time comes, but for vegging I'm looking for 6500K bulbs.

--Bud
I have the exact same bulbs in 5000K i use for vegging. Same wattage, same lumens.
 
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