Adam,
Since you seem to be extremely concerned about the tannins released by the wood, why not take it out of your tank, put it into a 5 gal bucket, and soak it for a few days? This should help eliminate the tannins being leached into your water. I have never used driftwood in my tank, but everything I have heard is they are safe for your fish.
As Wilder was saying, changing the carbon in your filter will help. I'm not familiar wiht your particular filter, so i need some help from you here. When you look inside your filter, exactly what do you see? For example, in my filter is a spounge for bacteria to grow on and a carbon filter. After about 4-6 weeks, the carbon stops working, so you need to replace it. I'm confused as to how long it has been in your tank. Exactly how long have you had your tank up and runnign for?
What I am VERY concerned about is the ammonia reading you are getting in your tank. Like all animals, fish go to the bathroom, and part of their waste is ammonia, which is highly toxic to them. In an established tank, there should be zero ammonia. What happens is some good bacteria grow and take the ammonia and break it down to nitrIte. However, nitrIte is still toxic to fish. As with ammonia, a reading above zero means there is a problem. Another set of beneficial bacteria develop and turn the nitrIte into nitrAte, which is safe for fish. The process of building up these good bacteria is called cycling your tank.
Because you have ammonia readings, this means your tank is not cycled. What you need to do is do partial water changes daily until your ammonia and nitrIte readings are zero. I would recomend doing a 25% change a day. Also, watch how hihg the ammonia level gets. If it goes above 1.0, you may need to do multiple changes a day. If this is the case, do no more than 25%, as it will stress out the fish, and wait atleast 3 hours between water changes.