How do I make my driftwood sink?

Alright maybe I'll let the pH slide for now since all other water params are perfect. I was shocked to be honest when I tested the water we had treated to put in the aquarium. I didn't know "city water" could be so out of whack. The Cardinals seem to be alright although I saw what may be an ick spot on the smallest one today, he's swimming alone too. Guess it's time for the hospital tank. Thanks for the advice though, it is helpful.
 
my tree stump has been submersed for over two years after boiling and it still wants to float slate, gravel and boiling and it still wants to float
 
AquariaCentral.com