first time grower...HELP!

Just starting out here. I have 8 plants each in a 5 gallon bucket. I am growing indoors under 400 watt HPS. Plants are at the 6 week of flower stage, if I can figure it out, I'll attach the pics I took...Damn stoner! Anyway, I am getting soem yellowing which has been explained, but notice this morning that I now have geen leaves drooping, sagging and dying off... Am I watering to much? 1 gallon bottled spring water per day divided between all plants. Fertilize with Miricle gro bloom booster twice a week.
Aside from the drooping the plants ghave done pretty well. I have some very nice buds working and am now only wondering when to harvest. I ahve a mix of seeds and understand they will mature at anywhere between 6-12 weeks of flower. I picked up a 30x mag. glass but can't make out the trichomes enve with that. Any other suggestions?

All info is appreciated!!
Thanks

they got a nice scope a radio shack for 12$ can make out the trichs perfectly trust me will definatelly help you determine when to clip.. helped me out a lot this being my first grow i had no clue when to harvest but yeah pick it up you wont regret it good luck!

Thanks Girl. Any thoughts on the drooping leaves?

i just had the same problem mine seemed to be from underwatering when i added water the perked back up within a hour... but from the plant problems thread ive read under watering and over watering look very similar and ur plants look very close to how mine did so maybe overwatering? :/ i dont wanna give ya bad info but thats the most i know! lols

Good deal, thanks!