a 600 watter will produce roughly 90,000 lumens...
you want 5,000 lumens / sq. ft for optimal growth....
that gives you coverage for roughly 18 sq. ft...

If you are able to fit those 15 clones in 18 sq. ft...you should be fine

:stoned:
DOUGAL25 Reviewed by DOUGAL25 on . Expectations?!?!?!? I have 15 clones which are about two weeks old that are under a 600 watt metal halide conversion bulb with an HPS Ballast. I started them in a soil mix specialized for staters and recently transplated them into Coco. Im also using rhizotonic for root growth along with the Coco A and B for food. I plan to begin the bloom stage in a month and transplant them into bigger pots. Should I get another 600 watt HPS or is 1 sufficent? If so, how big do you think my yield will be per plant? Rating: 5