Do i need to add Calmag to my tap water?

I use tap water, no calmag, and grow in coco. I never use calmag. But, 1 part of the 3 part dry nutrients I use is calcium nitrate so I'm getting plenty of calcium from that. So it all depends on what nutrients you're using as to whether or not you need any additional calcium. What I use is basically just Jacks with a slightly different formulation. If you use a nutrient formulated to provide everything the plant needs to grow using a soil less growing method like hydro, coco, or promix you won't need any additional calcium because it's already there.