25 grams sounds right, but I would leave them in there for longer than 10 days. Make sure the beer is completely fermented out before adding them. You could rack it off the yeast and into a carboy with the oak chips. I've read that the oak spirals are easier to add to a carboy. Haven't used them myself. Get French oak chips/spirals if you can. American Oak will give you some harsher flavors and tannins. Go with medium toast.
Without question, the greatest invention in the history of mankind is beer. Oh, I grant you that the wheel was also a fine invention, but the wheel does not go nearly as well with pizza.
- Dave Barry