Feed schedule during flower. GH cal-mag nutrient

mh is cooler white and hps is warmer... assuming you have 'enough' light in each phase you'd use the mh in vege and hps in bloom... if not enough light you should use both.. rotate plants around if you like to even it out over time. with that type of light tech, you proably need 50w/sq ft on a 12/12 light schedule.. .proportionally less for 18 hours. high end LED you can be around 32w/sq ft for a 12hour light schedule and proportionately less for 18 hours too, just the same. while providing same umol/s of PAR, you can spend 65% of the electricity... next time one of those short-lived bulbs go out, think about that a second. (led can* last 10x longer too) *not all LED are the same efficacy.. even if using the same diode... how hard they are driven and the temperatures they run will greatly influence actualy longevity, but in general, cost of ownership is much lower... produces much less heat (tied to the efficacy, as heat is ameasurement of waste)