Dichlor adds chlorine and stabilizer immediately, and lowers pH some later.

Once you've reached an adequate stabilizer level, you'll need to switch to cal hypo or bleach.

In some parts of the country, Walmart is selling 10% bleach for about $3.25/gallon in 1 or 2 packs as "Pool Essentials Chlorinating Liquid". That's cheaper than you are likely to find calcium hypo, since a gallon of 10% bleach is rough equal to 1.25 lbs of cal hypo. Also, bleach has virtually no 'side effects', where cal hypo will add calcium and raise alkalinity.

Regardless, I wouldn't mess with the Alk=70, unless you are having problems with pH instability.