400w or 250w?!? Any opinions welcome!

Would the yield difference be huge? My flowering chamber will be 6'6" tall x 3' deep x 4' wide. Would the 400w be to hot? I'll have good ventilation..and try to air cool the 400w.

This is gonna be my first medical grow and I wanna do it right.

this may help you https://www.rollitup.org/grow-room-design-setup/167842-air-handling-4x4x8-430watt-flower.html

Ummm...is there gonna be a huge difference in yield if i use the 250w instead of 400?

I'd use a 400. 120$ from HTG supply on ebay. Though I've read of some people having trouble with their equipment I myself have never experienced this.

hey goose,
here is my 2 cents. if you are growing strictly personal medical and can master a 250hps you can easily pull 6+ zips. if that ammount suits your needs, then go for a 250hps. you must be ready to lst your plants so that your light never goes above 5 inches from top canopy. i inserted a thread that goes over the 250hps and there are many pics of 6,8+ zips.
check the pics and thread out.

http://www.icmag.com/ic/showthread.php?t=22192&page=1&pp=15

I was planning on using the SCROG method...i think that would be the best way to make the most out of my limited space.
Thanks for the help guys!

Btw that link won't work for me alladin...try again =D

If you have good ventilation like a 6" cooltube and 6" fan then I would go with a 400w hps. Once you get good at growing you should be able to produce around 1 gram of marijuana per watt of electricity the light used. So your looking at potentially another 5oz going with a 400w over a 250w.

What's a cool tube? Is it expensive?

g00sEgg said:

I was planning on using the SCROG method...i think that would be the best way to make the most out of my limited space.
Thanks for the help guys!

Btw that link won't work for me alladin...try again =D

Click to expand...

then you will be needing the scrog bible.

https://www.rollitup.org/newbie-central/172536-good-scrog-bible.html

g00sEgg said:

Would the yield difference be huge? My flowering chamber will be 6'6" tall x 3' deep x 4' wide. Would the 400w be to hot? I'll have good ventilation..and try to air cool the 400w.

This is gonna be my first medical grow and I wanna do it right.

Click to expand...

if you wanna do it right get at least a 600 watt

Thanks Alladin...helps a lot!
Where are all the links he speaks of?

g00sEgg said:

What's a cool tube? Is it expensive?

Click to expand...

these are $85
http://www.htgsupply.com/viewproduct.asp?productID=48137

or you can make your own for about $30
https://www.rollitup.org/do-yourself/8503-build-my-own-cool-tube.html

LiEBE420 said:

if you wanna do it right get at least a 600 watt

Click to expand...

Wouldn't a 600w be way too hot for my small space?

12sqft / 400w = 33.33 watts per sqft.

Most growers try for at least 50w per sqft.

I've got 52w per sqft in a 2x8 closet with 832w of light, on average. where the light is actually concentrated is more like 104w per sqft.

KaliKitsune said:

12sqft / 400w = 33.33 watts per sqft.

Most growers try for at least 50w per sqft.

I've got 52w per sqft in a 2x8 closet with 832w of light, on average. where the light is actually concentrated is more like 104w per sqft.

Click to expand...

That's assuming that the entire 4x3 area is going to be filled with plants. He may have a slightly smaller surface area that actually needs light. Just out of curiosity, why do some growers use the 50w per sqft as a rule of thumb? Watts are not a measurement of light output but a measurement of energy used, wouldn't lumen per sq ft be a better rule of thumb? If you were to go by lumen per square ft then a 400w hps would deliver 4166 lumen sq ft in a 4x3 area. 3000 lumen sq ft from what I read is the minimum amount of light you want and anything over 6k-7k lumen per sq ft is overkill.

g00sEgg said:

Wouldn't a 600w be way too hot for my small space?

Click to expand...

I ran a 600w in a 3x3 area with a 6" fan and air cooled reflector and it worked ok. I wish I would have bought a reflector with 8" flanges instead of 6". If you use a 250w hps you probably won't need to air cool it but 400 or 600w you will need to air cool it or your temps will get in the 90s, will you be able to suck in cool air from outside the grow room to blow over the 400 or 600w lights?

Yeah i'm gonna be getting some inline fans soon...I'm thinking we're gonna go with the 400w.

"wouldn't lumen per sq ft be a better rule of thumb?"

Nope, because lumens is a measurement of green light, which humans are most sensitive to. Lumens combined with known color temperature/spectral output of the bulb would give you more of an idea of what you're after, but still not quite there.

As long as it is a gas bulb (fluorescent, HID, plasma) even with crummy T12 fluorescents, approximately 50w/sqft works very well for yield.

Potency is not necessarily strain limited, the other limiting factors in potency are UVB exposure and nutrients.

Mo' light, mo' bettah mon

As long as you can control the heat, that is. I run 1000w in a 1 square meter tent, with a cooltube+435 cfm Vortex fan. Temps inside the tent are usually about 2-4 degrees above ambient.

The girls love it

1000 in a 3x3 area = 111w/sqft

I want to see those mommas. I bet they're thick!

If you got the 250 watt you would be kicking yourself for not going with the 400 watt. If you got the 400 watt you may be wishing you got the 600 watt.
You just have to figure that the more light that can penetrate the canopy the better. As long as you can keep the grow area ventelated and cool, get as much light as you can afford.

Even If your only growing for yourself, I would go with at least the 400 watt. I'm using a 400 watt, and my last harvest with three plants in a 2x3x8 area, I ended up with just under 13 OZ dried.