I think the lime is great for soil, but it would wash right out of coco. Coco is essentially an inert hydroponic medium. You could add a bit of lime in every feeding but I think calmag solutions have the amounts figured out and include magnesium, so you are probably better off with them.
My first hydroponic grow was over 40 years ago! There was no information, no nutes, no seed banks, no nothing. Had to use Mexican bag weed seeds and get my generic hydro reagents from the lab supply store. Sand, multiple shop lights, and a little fountain pump on a timer, but it actually worked!