Sugar adds about 42 gravity points per gallon. So 2.5 lbs will add 105 points. Presuming this is a 6 gallon JZ recipe, this would add 17.5 points to your beer bringing you up to 1.087. That's a bit high, though better to be 7 pts high than 10 pts low on a tripel, I think. If it were me, I'd add 1.75 lbs of sugar. This ought to get you to 1.082 and will be enough to bring down your FG nicely.
Currently On Draft: Bamberger Rauch Dunkel, Belgian Blond, Pilsener Urquell clone, Smoked Porter
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