I have 9 pieces of driftwood in my house
1 small mopani leached tannin while boiling.. and is currently in slime mode .. It'll clear up on it's own, it's brand new - in my 5.5 NPT (and it wants to float so I'm weighing it down)
2 medium pieces of root I just soaked in room temp water.. never leached but had 2 small mold spots that cleared up .. - Currently in a 29 Tetra tank. Never tried to float
2 smaller pieces of root wood (same as medium listed above) .. boiled for about 15 minutes in a stock pot. Instantly cooled in ice water to harden and they sunk. Just put in a couple hours ago. Shouldn't leach tannin based upon above results.
3 large and 1 small piece are currently sitting in my 46 gallon because the pieces are almost 18+ inches long. New water every 48 hours and 2 100W heaters cranked up to maximum..
so some I prepped, some I didn't. I'm sure the stuff in my tetra tank would have leached tannin, but if it is currently I can't see it. I just soaked 1 of the 2 in a 5 gallon bucket for a week. If you can boil it in a large stock pot I would, even for like 15 min on a rolling boil. I'm sure that large nasties are dead in the wood, but you never know .. this would ensure death of nasties naturally without using chemicals. Also would help get sap out which causes white fluffies (bacteria blooms) but it seems that Mopani (the yellow/black wood) will develop a white mucus on it no matter what. It's normal and won't hurt anything.