How close?

i have a 400w hps w/batwing it is uncovered i have a basic fan that blows air over both the plants and the bulb how many inches away does it need to be i want to maximize lumens but not burn anything thanks.

I keep my lights about 18 inches away from the plants. But that depends on the size of them. In full Veg, like 13 to 18 inches tall. Now seedlings I wouldnt put closer than 24 inches away from a 400w. Thats just me.

Good rule of thumb, Put your hand on top of your plant. Feel the warmth of the light on the back of your hand. If its hot Its too close.

thanks that sounds about right im saving up for a 1000 or another 400w unit that is enclosed and air cooled my set-up now consists of 400halide/hps and about 400w of various spectrum fluoros how many plnts do you think i could reasonably get away with under said lighting i have 5foot squared grow room im thinking lots in small pots or afew in big pots i dont know which will yield more i have various strains to work with im in cali and am a medical user any advice is helpfull thanks again

I would figure One square foot per plant container. 400w would cover six containers in two rows of three. So a 2x3 area. Now you can use some floros outside the 400 to veg with. But when you go to flower you want your best plants right under the best light.

You could put up to three plants per container and then weed out the runts. When they take off you are going to need some room.
I was always told to go one plant per container but there has already been a time I wish I had planted a few.

The deal is the indoor lights just dont have enough power to get to the sides of the plant. Once your plant is 2 feet tall the lower buds are 4 feet from the light. Every foot loses lums not sure exactly how much but if you figure 50% at 4 feet your close.

Again, thats just my experience. Im just starting my second grow but I am a quick learner and picked up a lot from here and just thought I would give some back.

If you live near Oakland they sell clones at the co-op downtown.

Check out the FAQs here. Good luck!

thanks for the advice oakland is far for me but its ok there are over 400 co-op's in the los angeles area its amazing they give you free stuff just to get you to stop im hoping my o.g. kush's do well i have other strains to but i want them to do well in particular they get favorable placement. i plan on getting a 2nd 400w soon until then i will use the 400w of fluoros for increasing bud sights on the lower portions of the plant so the halide will be shining down and the fluoros shining up hopefully i get decent coverage and better yield on the lower branches i definetly can see faster bushier growth with the added fluoros than with the halide alone also when i flower the plants will get 400w of hps but also a complete spectrum from the fluoros they are expensive aquarium lights desinged for corals which are a much bigger pain than cannabis. anyways somewhat of an experiment but i think the blues and reds during flowering is better than reds alone for resin production. 6 plants is probably about right i will have to give some to a co-op.