I never use activated carbon in my tanks because i don't believe it's necessary. However, my tank water has a yellowish tint due to tannins from my driftwood which i would like to get rid off. I'm tired of just waiting for it to just go away. How effective is using activated carbon for this and on average how long does carbon last before it stops working and needs to be replaced? Also is there any other method i can use to get rid of the tannins?