I've read that malic acid capsules are not as effective as the powder form diluted in water (which can be purchased from piwine.com or bulkfoods.com) Half to one teaspoon in 24 to 32 oz. water.....Apple juice is another option to prepare for the flush as it contains plenty of malic acid, some people alternate malic acid when the juice feels like too much sugar. There's also cranberry juice and apple cider vinegar. But apple juice is said to also dilate the bile ducts, remove stagnant bile and even cleanse the bowels due to fermentation -diarrhea being thus a positive sign-. This amounts to a few days preparation before each flush, rather than an ongoing dose of acid. This may prove crucial to help you release lots of stones. Best of luck with any approach you choose.
(Also be sure to look into Miracle-Mineral-Supplement -the Miracle Mineral Supplement, one of the fastest-acting detox substances one can get. Sadly it's currently going through an expected crackdown by the FDA, and becoming scarce as vendors are being threatened. Still it can be easily home-made and you can readily find information and testimonials about the many it has helped).