I've been exploring hydroponic gardening lately, and thought y'all might be interested in hearing about my setup:
Then install the fan... I put mine on the top of the box, but It could go in the top back corner if light leakage is important. A good deal of light will be exiting the fanhole (well, more than anywhere else)... keep this in mind. I also painted the fanblades white in an attempt to reflect the light back into the box, but I'm not sure if it worked... it probably isn't necessary.
Put some intake holes along the bottom of the box, these will be covered with foil later, so not too much light will be leaking out.
Cover the entire inside of the box with foil, excluding the fan area, and where you plan on installing the lamp. I used duct tape to affix it to the walls/door, and I left it unattached at the bottom so air could come through the intake holes.
Install the lamp! I put mine at the very top center of the door, with the bulb sticking straight out, so it enters the rest of the box when the door is closed. This made it easier to wire, but In the future, I would put it on the back wall of the box, as less of your room will be illuminated when you open the thing (it's kind of like opening up the sun).
I used a Flurescent to sprout the plants, and switched to HPS after they had developed 3 sets of leaves (about 48 hours after germination) This was acceptable.
Next, it is time to deal with the foam and plant. I soak the foam overnight in a nutrient-water mixture (more on that later) after rinsing it extremely well. Then I cut a brick or 2 into 1" cubes, and plant one seed in each cube. Planting in foam means you place the sead on the foam, and push it in with a small wire or something similar, so the seed is surrounded as much as possible by the wet foam. The cubes are placed in the dishpan, and 1/2" of water-nutrient mixture is added to the pan. The foam will suck up water and nutrients as necessary, so it is important to try to keep the water level at about 1/2". It is better for the water to be slightly too low (but not dry) than too high.
The seeds can take as long as a week or 10 days to germinate, do not worry if nothing happens at first, and it seems that I never get more than about 15% of my planted seeds to sprout. This suggests a fault somewhere in my system, but I haven't identified it yet, no do I especially care. I just plant a lot of seeds, and then use the best seedlings for my gardening. Usually a smoking-buddy or someone will take a free marijuana seedling off your hands with a minimum of hassle.
About 3 days after germination, a few pairs of leaves should've formed. Now is the time to transplant. And transplanting is the glory of foam. All you need to do to transplant things growing in foam, is put the small block of foam (with the plant in it) on top of the larger block , and rub them together a few times. The roots will grow out of the small cube, and into the bigger one in a matter of days. I managed to find foam in 12" cubes... cutting these in half gave me 2 pieces of 12"x12"x6" foam, and each of those can easily hold one plant, probably 2. I personally grow only one plant in each trunk, but 2 smaller ones are probably perfectly acceptable.
When I transplant is when I turn on the HPS lamp. It then stays on for 24 hours/7 days until the plant is 8-15 inches tall. Then it is time to force flowering. This can be done by giving the plants a 10-16 hour dark period in each 24 hour day (this should be done using a cheap timer like people use when they go away on vacation in an attempt to foil burglers) In a matter of 3 weeks, sex should be apparent on the plants... Remove the males. Keep the dark period constant until it is time to pick, dry and enjoy.
Floram foam should be totally inert, meaning it does not provide the plant with anything except something for the roots to grow in. Thus all nutrients that the plant would get from the soil must be in the water. Read a few books on hydroponics to figure out what mixture suits you best, I personally use a liquid plant food that shows on its label an N-P-N count of 10-15-10. This seems to work fairly well for me. I know people who use 20-20-20, and quite a few who use different foods during different stages of growth. Read up on the subject and decide for yourself.
Anyway, this was not meant to be a 'HOW TO GROW WEED' type of post, but apparently it has become one (sort of). It was meant to talk about my grow room, as it was described earlier in this post. I have found that a single plant can grow to maturity without any trouble in this space, and 2 smaller plants (forced to flower at about 8 inches, instead of the 10-12 that I personally use) would probably be ok too.
This grow room is very portable (unplug it and take it with you) clandestine (it looks like a trunk to me (not an uncommon thing in a college dormatory if you are a student), and it can be locked with a padlock) and effective (trust me!)
I assume one could grow using standard soil and such in this thing, but I have had great success with foam, and it is much easier to keep it watered. Rockwool has been sugested to me as a medium, but I don't even know where to buy it... apparently it is much like foam in that it is inert, and transplanting is a breeze.