Charcoal will absorb toxins and help to avoid root rot. It will deter fungus and bacterial overgrowth.
Pre-bagged charcoal comes in a resealable bag.
If you are shopping in-store you can buy charcoal by the scoop (1 L per scoop) and take them home in your own reusable container.
Bring your own container to fill and save 10% on all soil bar products.