The lights are dependent on what part of the cylce your plant is on , or if its an auto then it dont matter at all you can leave them on 24/7 but basically the table runs 24/7 and when its time to add the nutrient solution it will be in the water until either a) the plants absorb all of it or b) till you do a rez change which i would recommend doing min 1 a week . Other then that a hydro table pretty much takes care of itself . I would check the PH every other day to make sure its always consistent but other then that your well on your way to getting some kick ass medicine ! I hope this info helps you -Happy Growing!