For the most part, liquid bleach is pH neutral. The main reason you want to drop your pH prior to SLAM is that you won't be able to achieve accurate pH tests with a FC level over 10 ppm. Lowering pH buys you some time since you won't be adding MA during the SLAM. During the SLAM, you'll only need to test FC and CC. Since you have smaller reagent bottles, make sure you use a 10 ml sample for FC/CC testing. When you get your FC up into SLAM range, you can even use a 5 ml sample to save reagents. Use one scoop of powder and each drop will count as 1 ppm. When a more accurate test is required (like the OCLT) go back to using a 10 ml sample.
Use only liquid chlorine bleach. Shop around for the best deal, but be aware bleach comes in different strengths from 6% to 12.5% and the amount used for dosing will depend on that strength. If you use household bleach, use only plain, scentless bleach without additives. Do not use Clorox bleach unless your goal is to make a bubble bath. When you buy liquid chlorine/bleach, check the Julian date and stay away from products that are older than 3-4 months. The Julian date will consist of 5 numbers. The first two are the year and the last three are the day within that year (19 030 is the 30th day of 2019).
Follow SLAM instructions carefully and test and often as you need to maintain FC at SLAM levels.