I'm using Walmart bleach (unscented)....I don't imagine I will get much customer support
My normal chemical of use during water treatment is H2O2, and I use food grade stuff for that. But for shocking, I used the cheapest and what was readily available.
I'm using Centaur Carbon. I'm around 6 years in on this carbon. I hit it pretty hard with chlorine this shock treatment, but I had some slime in the system. I've been wondering if there is such a thing as overdoing it because if there isn't, I could theoretically run all the nasties from the shock chlorination back through it. I did run some out on the ground.