yea .. and keep it at a fare distance to start with .. I dunno how many watt .. or if you got a cool tube ?
but lets say 400W with out it ..
then I would maybe start with 20-25 inch`s and move it closer evry day untill I can keep it at the distance I prefere ..
(15 inch`s .. maybe 12 with a cool tube)
you can actually start your seedlings under a MH from the beginning. just keep it a far distance at first. i did my first run a long time ago. start like 3-4 feet away with a 400w. http://skiweeds.angelfire.com as you can see mine were fine. on the other hand though, your CFLs probably cost much less to run obviously depending on the wattage and how many. MH has more lumans per watt than CFL which will make your plants grow a bit faster tho.
personally i only like CFLs for propagation. i use either t5s or hps for seeds and veg. used to use mh but for some strange reason it seems like hps works better for me than mh. i know the spectrum isnt the greatest for veg, but it does put out more lumans per watt than a mh.
i place my seedlings in styrofoam cups beneath a 1000 watts as soon as they shed their seed coating
i place the styrofoam cup in the pot of another smaller plant
approximately 24-30 inches from the light
the sun is a HELL of a lot more intense than cfls or 400 watts at 3 feet
beer has it right. You can put your seedlings under that MH whenever you like. The only reason to keep em under the cfl's for any longer would be to save money on power costs. Common sense should tell you not to put your light too close to any plant of any size. So the guys that said keep a good distance were also correct. I start my seeds under t-5's until they get too big to fit under those then they go to MH.
Shag said it all. right on dude you get some common sense rep!