400w or 600w?

It seems that the 4 ft. x 4 ft. mark is the grey area between a 400w and a 600w system. All thing being equal, I would prefer the 600w; however, I do have two concerns:

1. Heat. It seems that many of you with a 400w can get away with using a standard fan to cool the bulb. Will a 600w require glass and cooling ducts... just glass with a standard fan... just a fan? If it matters, there is plenty of room above.

2. Power spikes. I appears that the difference in overall power consumption is negligible between the two. But, what about when the bulb ignites? Some of the recent threads say that under a 1000w is nothing to worry about, but is there a noticeable difference between a 400w and a 600w.

I'd appreciate any thoughts.
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The 400 watt will give you around 42000 lumens, the 600 wat will give you 90,000 lumens. 50% more power consumption, 100% more light. The difference in heat output will reqiure that you put it about 2" higher than a 400 watt.

VictorVIcious said:

The 400 watt will give you around 42000 lumens, the 600 wat will give you 90,000 lumens. 50% more power consumption, 100% more light. The difference in heat output will reqiure that you put it about 2" higher than a 400 watt.

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So, the 600w will not require glass and air cooling ducts?

go with a 600 digital ballast..they produce withing 5% usable light as a 1000w magnetic core ballast. a 400w is to small for a 4X4 area in my opinion. im in a 4X4 area and just switched to a 600w from a 1000w. and this is coming from someone who owns a 400w, 600w, and 1000w.

Personaly for 4x4 area i would use 1000watt AIRCOOLED digital ballast MH/HPS conversion. My grow room is a 5f x 6.4f x 6.8f i have a grow tent in there a big one. and i use the grow tent for veg-flower, and outside the tent is where the mothers chill with some 4 foot T-5's and teh clones.

in the veg-flower area i use dual 600watt's mh/hps digital, everything is aircooled and ventilated, with a coco carbon filter. and the mother and clones done give off enough smell to put another cococarbon. but with one t-5 4f 8 bulb HO FLuro, and two 600watts im lucky my rents dont catch on. but i do a good job in keepin the rest of the houses lights off. and we use CFL's for everything pretty much. but my setup works fucking wicked, but is currently not in use untill the next couple days

just somthing you can build up too, in total i've spent $2,000 canadian over time.

Ok, the consensus is 600w. Can I get away with using a standard fan to cool or will this require duct-cooling?

for optimum setep you are gonna want duct cooling but its not a must. I would highly suggest it.

600 watt is what i would go with if i had it to do over. Yes you will need to vent. It is SO important. Proper venting and air flow could mean the difference between a great crop and a diaster.

If my memory serves me correctly, the 400 watt system is only good for a 3.2x3.2' area. Your area is slightly bigger. So, yes the 600 watt system. You can get one at a good price. Get the glass too.

videoman is correct get one with the glass that will help you vent the extra heat

i have a 600w in a 3 x 3. i bought the glass, the fittings, the duct the outake fan. hooked it all up. my room was TO cold. so now i have the duct hanging in the top corner, detached from the light, with the fan running 24/7.i also have 2 mounted desk fans that come on with the light. the glass is still on. my light is 20" above my tallest plant. the temp is just right.

very nice, i have the same problem during the winter but in the summer im fine, thats a good way about doing it, i went out and got a Heater to heat the room every 15-30... i should of just removed the glass.. meh too late

TillthedayiDIE420 said:

very nice, i have the same problem during the winter but in the summer im fine, thats a good way about doing it, i went out and got a Heater to heat the room every 15-30... i should of just removed the glass.. meh too late

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leave the glass remove the duct.

"my light is 20" above my tallest plant. the temp is just right"
Dude, thats pretty far away.

videoman40 said:

"my light is 20" above my tallest plant. the temp is just right"
Dude, thats pretty far away.

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20" for a 600w is about right. in a 3x3 with mylar on 3 walls. i could be wrong.

fdd2blk said:

20" for a 600w is about right. in a 3x3 with mylar on 3 walls. i could be wrong.

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fuckin' stoner i am. i'm wrong. 20" from my smallest plant.it's about 6" from the tallest.

videoman40 said:

"my light is 20" above my tallest plant. the temp is just right"
Dude, thats pretty far away.

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still really high but wait a minute. BULLSHIT!!!!!!!!! where do you get your info?

IN FACT WHERE DO ALL OF YOU GET YOUR INFO?

everyone seems to really be on the jump to correct and condemn people lately. sorry video you just happen to be the last straw.


i just got off my lazy ass again. i went outside to my room. my light is 20" above my garden. i rotate plants so some are short some are tall but i use blocks to get them somewhat even. the heights vary about 8" from the shortest to tallest.

when i hold a tape measure from the corner of the hood to the outside corner of my tallest plant it is 20". that is a diagonal measurement. but if you sweep an arch down and in................

i went thru a few books i have laying around https://www.rollitup.org/general-marijuana-growing/7462-everything-i-know.html and the recommended height from plant to light for a 600w is 20 - 24". it can be placed closer if venting is used. i'm not using my venting. i need the heat.

Dude, dont get your panties in an uproar. I was not trying to jump down your ass at all, nor was I condemming you.

I was however trying to be an assest to this community and offer some help to a fellow grower, thats all.

While 20 inches is okay, you can get alot closer, and the tendency is to get as close as possible for light penetration.
(as long as heat is not a problem)

Here is the reference for my opinion, feel free to use it, the source of this light chart is cannabis culture magazine. (giving credit to the author)

I appreciate everyone who took the time to reply.

Good luck Billy! Keep us posted as to your progress.