15x Critical kush grow

Hello guys!
This is my 3rd grow, and this time I'm going to record it all on here. My first grow was 3x OG kush and 3x barneys blue cheese - in coco and under 600w hps, yield was 12oz dry.
2nd grow was 4 blue cheese clones (15l pots, coco, 600 hps) yield was 18oz dry.
Now I've just cracked 15 Critical kush seeds, and I've bought a lovely new T5 4ft 8tube for seedlings. I will use metal halide thru vegging and then hps for bloom. I'm using coco/perlite mix at 70/30. Tent size is 1.5m x 3.0m x 2.0m.
I'm wondering how much light I will need through vegging and bloom. I'm thinking maybe 1500-2000w?? The strain info says 750g per m2, which would be over 1500g. But then on my last grow I achieved 0.75g per watt. How much light will I need to maximise yield? Any questions, input or advice would be most appreciated :-)
Photos of last projects as well as pics of this current one will be uploaded soon.........
 
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