can i add the tannic water that boiled off ...

Bad idea. Water stability is more important than a one time impact. if you dont have the ability to maintain the water quality, dont make a one time change.

I added a piece of drift wood but boiled it before putting it in to kill off any bugs or parasites. It was bought at the lfs and was marked as clean and for aquarium use. My question is can i add the water to my tank a little at a tine over the next week to get that blackwater look. I have german rams ,bolivian rams and two very nice breeding angels, Sarpea tetras , cory cats and some black skirt tetras. Ohh and a small rainbow shark. Do you think it will negativley affect any of them.