Originally Posted by Dogphish
you should leave all beers in primary for a full 4 weeks so that they yeast can finish and settle out of the beer.
you should not add yeast to secondary, you should just leave in primary longer.
if the hydrometer reading has stopped changing for 3 days straight, then adding more of the same yeast will do nothing. if the hydrometer reading has not stayed constant for 3 days, then you racked to secondary too soon.
I know at least one moderator here who would disagree with the 4-weeks figure, but it certainly doesn't hurt. I'm thinking this was racked way too soon. If your recipe really is a DIPA, 5% is about half of what you're looking for (maybe a bit more).
A single hydrometer reading doesn't tell you much about whether the yeast are done, that comes from observing several days in a row and looking for no change. We really do need to know all the details. The blow-off could have played a part, but without knowing times, gravity measurements, etc. there's no good way to tell.