Just started an experimental 2 gallons...
It's often said that supermarket AJ lacks the malic acid of cider apples, so you should add some (and then leave it months for malolactic secondary fermentation)
So I did a bit of Googling and found
http://www.cider.org.uk/frameset.htm (and a few similar)
And it seems in fact supermarket AJ is MORE acidic that a good cider juice blend.
What's going on? Well, most of the people saying "add malic" are doing MLF, which reduces acidity...
I don't do MLF. So...
1 gallon with 1tsp calcium carbonate (that's chalk to you), 1 with 2tsp. To see what happens if we reduce the acidity up front.
Results in 6 weeks.
[1/2l blueberry, 4l Morrison's Saver AJ, 1tsp tannin, 1tsp nutrient, half sachet Young's cider yeast, plus the chalk]
Seen something suggesting potassium carbonate may be better than calcium carbonate. Wondering about sodium carbonate, or even magnesium carbonate. Maybe not lithium carbonate...