Arsenic comes in two main flavors: arsenic III and arsenic V. Think of them as the evil twin and the slightly-less-evil twin.
Arsenic V (pentavalent) is the easier one to remove—it’s already charged up and ready to be caught. Arsenic III (trivalent) is the ninja: uncharged, slippery, and way harder to trap.
Most basic filters only handle Arsenic V. For the full arsenic annihilation, you need a filter that tackles both types. Otherwise, you’re just waving at the ninja as it swims past.
