Is one Calcium Nitrate? Read the label.. should have chemical analysis of what is in it.
add that one after the first is well-mixed. The problem is Ca interacting with Sulfur for the most part, but only at high concentrations. If there is an order, it is to avoid a precipitate like this.
https://www.amazon.co.uk/Hornet-Hydroponic-Industries-CoCO-Parts/dp/B01M1VBJMC
check lower "must add a before b" [sic]... Mix A well, first... then add B