Time to get started, but first....some questions.

Hey everybody. Work has finally slowed down and winter is quickly approaching. Time to get some work done on the new grow room.

I still have a bit of work to do, and I will surely be posting pics, but I'm wondering if a 400 watt hps is going to be to much.

The room is 2' x 3 3/4' x 6 1/2' tall. So that's 48.75 cu.ft. with a 7.5 sq.ft. foot print.

I will be using passive intake holes and a carbon scrubber with an exhaust fan. I'll post some other thoughts and pictures soon.

Thanks in advance.

Never too much light if you can control the heat. Buying aircooled lights were the best investment I've made.

I use a 400W with a cooltube in a 2' x 3' x 40" space w/o any problems.

Ok, sounds good. Something like this?

http://cgi.ebay.com/400-WATT-HPS-AIR-COOL-TUBE-DIGITAL-GROW-LIGHT-HOOD-400W-/400164755561?pt=LH_DefaultDomain_0&hash=item5d2bad9869

or http://cgi.ebay.com/400-WATT-HPS-DIGITAL-GROW-LIGHT-6-AIR-COOLED-HOOD-400w-/160493306462?pt=LH_DefaultDomain_0&hash=item255e25825e

I've seen that lots of people like the air cooled hood more than the cool tube. Reasons why?

I'd like to only use one exhaust fan for bulb cooling and carbon scrubbing. Which one will work best for that.

btw, I'll be starting with a 3 plant grow in soil for my first hps experience, than maybe do a 4 plant bubbleponic Scrog.

Little help?

The hoods seem to run a little cooler, I didn't have room in my cabinet (see pic). Either will work, the cooltube is probably a little easier to setup the way you mention carbon filter : light : exhaust but you might have some issues setting it up in that small a space. Sounds good, best of luck.

The fan will likely be mounted to the ceiling of the grow room with the carbon scrubber attached directly to it. In that case, I'll have to build an in line version of my scrubber.

However, I don't know if one fan will be enough to cool the bulb and pull air through the scrubber.

Any thoughts?

Anybody have the cfm chart handy?

You can get a fan big enough but it'll be expensive. I used two fans, one for the light (closed system) and one for room exhaust to save a little money. What cfm chart? Calculate your cubic footage, multiply by 5 then add the drop caused by the scrubber and any sharp bends in your ducting (~ 30% loss/90 degree bend). Some people say you need to turn the room air over more, I think 5 times /hr is enough.

So the cool tube is a closed system?

Usually though it doesn't have to be. I take fresh air from outside the cabinet through the cooltube then out , my room ventilation is separate and vents through a DIY carbon scrubber. Another common approach is to connect the carbon scrubber to one end of the tube inside the room & pull air via a passive intake through the room, through the scrubber across the light then out. I don't like that because if you have a humid environment you can produce condensation on the light when it goes off. I also like a certain amount of redundancy to my systems... There are no hard and fast rules (despite what you may be told) and you should try what you think will work best, don't be afraid to experiment, you might come up with the next innovation.
A thought on your light: my 400W ran a little hot to the touch right under the element, I added a small piece (4" x 6") of plastic diffuser lens (for overhead florescents) by just wiring it to the outside of the tube. Best of luck, looking forward to seeing it.

I think I'll do the two fan thing. Pics tomorrow after I get some work done on it.