CaCl is not enough , u must make the brine acidic, the brine should be as acid as much as cheese, so for home cheesemakers, use the same cheese whey as brine (it has Calcium and acid) so no need for CaCl and acid. just keep in mind that u should save the whey and holdit in closed container beside the cheese while it is in room temp, so both will reach the same acid (same temp , time) , so when it come to brine time in fridge, add salt to whey, put ur feta inside the brine-whey and store in fridge.
cheers