yes/no, for me it wont be, and i think there is cal mag in the pure blend pro already, i belive i read it off the label. I have so much awsome stuff in my water as is, if i added any more additives other then nutes to it i would lock up alot. If your using tap water, i would say if u read out a ppm of lower the 200 it might help, but i dont think u will notice a change. the calmag is for ro or distilled water, and products such as pure blend pro include it in there formula for there source of mg and c