Personally, I start with a clean steel-bristle brush and scrub every square inch of the wood to clean it up a bit and prep the surface for a good soak. (High-grade wood should have been scrubbed and pre-washed by the company of origin, but I like smoothing the wood even more to protect my fish) I boil my wood for about 1-2 hours and then let it soak in the tub over night--maybe even two days if the tub water is initially a dark tea color (which it usually is). More times than not, the wood may still tint your tank water. This is not a bad thing but, as mentioned above, it will lower your pH a bit. However, I tend to think the wood itself will do that over time. The tannin release is a defense mechanism to prevent organisms and such from "eating" the wood. Even in death the wood fights on!
Few tips:
-Don't put "found wood" in your tank. These may harbor parasites. If you must insist on putting found wood in your tank, scrub it, boil it and boil it some more. Opinions may vary but, generally, the consensus is nay. If the wood was found dry, different organisms may be present and could pose an entirely new threat to your tank. Bottom line: User beware!
-Don't put over-sized pieces in your tank. More size means less water! Your
bio-load capabilities will drastically change and your tank may become severely over-stocked virtually overnight. I have a fairly large piece of wood (40-50 pound piece) in my 120gal that seems to displace up to 10-15 gallons of water. Ideally, buy the wood before cycling the tank so that the bio-load and wood develop together. The filter will then establish to the actual capacity of the tank. However, since the capacity will reduce by adding the wood, it's not required. I just like that fact that the tannin-stained water is gone by the time the tank finishes the cycle.
-Tea-colored water looks like , despite some opinions. Good news is, it won't last. Water changes will gradually reduce the amount of color. Also, it's very common that a silky white fungus will start to grow on your wood in a couple days. This is normal and should disappear. A second boil should eliminate it for good.
-You may want to add just a tad of water conditioner while introducing the wood, especially in smaller tanks. Depending on the size of the wood, there may be a slight amount of tap water contaminants. Nit picky, but worth mentioning.