[BillA]

chemical resistance is related to concentration, temp, and exposure time
bleach is sodium hypochlorite and the stuff in supermarkets is 2.4 to 6%
(and you thought it was all the same, eh ?)

do use google to evaluate what you are putting into your system vs. all the matls in your system

6% bleach and copper will turn your water black pronto, and cause verdigris on the brass bits
not good (the goal is to clean, not etch)
a chemist can detail what's happening far better than I

- the fish guys have NO copper (nor brass I think)
and bleach will not remove adhered gunk, same old problem

20 to 25% glycol is good (do NOT mix the old green and new pink stuff, not compatible)
I think the pink is less (non ?) toxic