Horticultural Activated Charcoal

Charcoal acts as a filter to absorb impurities in water and improve air quality

It is excellent as a layer in the bottom of containers and in terrariums where water may pool because of no drainage holes

Charcoal also can help absorb impurities in fertilizer

Comes in 2 sizes:

Small - 10oz which is approx 3.5 cups
Large - 1lb for larger planters