From an efficiency stand point PJ Diaz is correct, although a 400W will give you some decent results its not going to be superb, if your looking to maximize the results go with a 600W or 1000W, the 600W is the most efficient in terms of lumens per watt.Do what you want, but once you get past the reading portion and move on to the actual growing portion you'll discover that a 400w won't fill a 4x4 space with light. My 400w fills a 32" x 32" space perfect. I have a 600 in a 4x4 space and even that doesn't completely fill it with light. There's a definite drop off at the 8" or so perimeter of my tent. You can go ahead and if the space with plants, but your lighting won't be optimal. Will they grow and give you lots of bud? Yes. Will they grow to their maximum potential? No.
without pics its hard to say. I'd guess somewhere between 2 and 6 oz.This will be my first harvest with two thirty inch plants what kinda weight can i expect with 400 hps
If your a legal medical patient staying withing your limits then yes absolutely (although if your not careful it may increase the chances of rippers finding you), if your not however then I suggest you disable the Geo-Location feature on your camera (if it has it) and just make sure there's nothing specifically in the pictures you take (its mainly stuff in the background you don't think about like pictures of you on the wall, mail or magazines with your address on them or geographical land marks seen through windows etc.) that could lead LEO back to you and you should be fine, Ive heard reports of LEO using pictures on forums to bust people so it dose happen.Is it safe to post pics here?
Your gonna want to keep that 400W as close to them as possible so just do the bear hand test, hold your hand under the light and if it doesn't burn you your plants should be fine, having an inline fan hooked up to your hood will allow you to put it a lot closer to the plants.How close should i keep the light i have that hood that you can put a booster fan on to suck the heat out when its to close i feel that the light isn't spread as much what right height for 30 inch plants?
That's exactly why I was saying a 400w won't fill a 4x4 space. 15 inches is too far away for a 400w to get the lumens you want on the canopy. A 600w would be fine at 15 inches. IMO, you don't want a 400w more than 12 inches from the canopy. There's a lumens to distance chart floating around the net somewhere.When i lowered the light it didnt seem to spread all over the plant I have one of those air cooled hoods I think that might be limiting the light i have it about 15 inches right now because it gets the whole plant and at its brightest point on the whole plant would that be ok or make the top buds smaller plants not really growing taller.