I have a 6.5' tall chamber with 16 square feet of floor space. I want to grow 9 or 10 plants in there under a 600 w HPS, 97,000 lumens, extra red and blue spectrum. I have the set up, and I'm waiting on a dispensary to prepare my clones in 2 weeks. I have 10 quart pots and coco. I'll be investing in good nutes later this week. How high should I grow my plants before shifting to 12/12...I think I've read 18" is good because then the plants may end up being around 3' tall. Does this sound right? Should I aim for taller or shorter given the number of plants I'm growing. I may ask a few more of these short questions as this is my first grow and I'm ironing out the details while I wait for my clones. Thank you for your time and feedback.