You should get .5 grams per watt of light at average. You have 1800 watts so you should get 900 grams per grow. You can put alot or just a few plants under them and get the same results, just depends on veg time. Some pic's of how you have them setup in your room would get more help than just guessing. We have never rotated plants in flower, seems to just mess them up to us. Maybe a sun mover but with 3 light you don't need that.