There may be some confusion about all the products called "Shock" but I just saw a gallon of 10% bleach at the pool store and it too is called "Shock". But at $4 a gallon it's a bad deal compared to $2.40 for a gallon and a half for the 6% ultra-bleach.

The bleach calculator indicates 19 ounces to raise my 15,000 gallon pool by 1ppm using the 10%, and 24 ounces using the 6%. It works out to 58 cents a dose for the 10% and 33 cents a dose for the 6%. Assuming I did the math right...