You can't really age the piece without dropping it in a stream for a couple of years. If it's "green" enough that a visible fungus is attacking it, you can't get away with boiling the piece. Boiling will only cause the green wood to break down even faster in your tank. Per Wyldfya's advise, get a proper piece of wood for the royal. Alka-seltzer? (I guess you mean algae wafers) food alone won't give the royal all that it's looking for.