I hope you can help me...
I'm trying to make the following recipe for hard cider.

1 gallon pasteurized apple cider
12 ounce can apple juice concentrate
1 cup white sugar
Champagne yeast

Pour out enough cider to make room in the jug for the concentrate and
the
sugar and the re-hydrated yeast. Mix thoroughly and put an airlock on
it.
Come back about a week later, check the gravity and if it bottoms out,
prime it with 2 1/2 tablespoons of white sugar, then bottle it in two
2-liter plastic soda bottles. Let it condition for about a week

After 8 days in primary fermintation the cider is bubbling like crazy.

I'm afraid to add the 2 1/2 T of suger for the secondary fermintation
for feer of an explosion in the bottles.

Any help would be GREATLY appreciated/

Thanks,

Bruce