If it is wood from a store, then the main reason for boiling it is to get rid of the tannin, the acid that will turn your tank a dark tea color or yellow.
I used to boil wood at a slow boil in a big pot for 2 or 3 hours. I don't know if it has to be that long or not, but it worked! It killed the tannin and also made sure the wood became water logged. Small peices of hardwood or "swahala" wood can sometimes still float, but after boiling they sink. For wood too big for a pot, I have run it thru a dishwasher or even in a laundry washing machine, without soap of course.