From what I've read its the best water soluble way to get calcium to your plants. I have deficient fruiting plants out in soil that need it and I was going to supplement my new DWC grow with it.
I read yesterday it can be used as an oxidizer for explosives, if that's what your getting at, lol. If that was the case I would be going to the place that sells the 25kg bags and I would be using Ammonium Nitrate instead ;-) , but I just want a kg of Calcium Nitrate and GH CALiMAGic is such a rip off when Calcium Nitrate and Epsom Salts will do the job.