It hurts...your wallet. 
Activated carbon loses it's "cleansing effects" 2-3 weeks after you use it. Useful for removal of medications or tannins from the water.
Otherwise, I'd stick to Purigen since it's rechargable, and IMO, does a better job of making my water look clear. If you have a bad tannin problem or medication, I'd still throw a bag of carbon in for a few weeks or so, in addition to the Purigen.
Activated carbon loses it's "cleansing effects" 2-3 weeks after you use it. Useful for removal of medications or tannins from the water.
Otherwise, I'd stick to Purigen since it's rechargable, and IMO, does a better job of making my water look clear. If you have a bad tannin problem or medication, I'd still throw a bag of carbon in for a few weeks or so, in addition to the Purigen.
