sounds like both a water born alge bloom & leaching tannin. is this tank near a window? sorry if i didn't see this in the posts, what size is the tank? also in my 20yrs of fish keeping i've NEVER had water born alge bloom. this is y i ask about being in direct sunlight. as for the tannin's you should be good after awile of water changes. did you presoak the wood before adding to tank? i once didn't do this, and caused my tank to be as dark as tea and was hard to see in tank. this lasted for few months, but eventually disappeared.