I know the reasoning behind using RO. If you have decent water from the tap there really isn't a need for using RO. If you use benificials just make sure you let the water sit for a day before adding them because the chlorine will kill them. I use house and garden which also has mag+cal added and I still ran into deficencys from time to time. Seemed to be strain Dependant. When using tap, I never see this, ever. My bottle of calmag has been collecting dust since switching back.RO puts the grower in control of what (and how much) to add to the water base. There is so much crap in tap water, as well as the fact that the percentage of Ca + Mg is not dialed in either, and of questionable quality.
I use Hydroponic- Research VEG+BLOOM RO formula, which includes the correct amount of each for mj.
Im just wondering if its really the LEDs that need added cal/mag or if its just unbalenced nutes.