Hey there maryjanenewbie,
The size of 3'6" X 4'9" for a 400 Watt Hps sounds perfect. Be very cautious about the distance that you keep the light above your ladies. Also watch your temps close, 74*-78* is right in where you want to be. The temps for your dark cycle can drop down to 68*-72* will keep them happy,
I am a tad concerned with the number of ladies squeezed in there. Seems like to many for the given area to me.
I have one white widow, and four Blue/Mystic in mine, and mine measures 3'6" deep X 4'6" wide X 6'6" tall. My babies are 2'6" tall give or take, and they fill all my space. I do suspect that I will find one or two males in there, though I hope not.
I just flipped mine today, and expect to see what I have in approx. seven to 10 days. I am also running a 400 Watt Hps, so this might turn out to be a lot of fun comparing what we have done. My W/W is a clone from a female that I had, that suffered very bad nute burn as the strain is very sensitive to it. I did take several cutting from her, but lost all except the one which is doing real well so far.
I look forward to hearing more from you, Thanks for sharing with us.
Looks like we both picked up some good MOJO huh ?
smoke in peace
KingKahuuna