We just started our second batch, a Belgian IPA with high alcohol. It was in the primary for two weeks, and last night we transferred it to the secondary and added in dry hops.
The SG dropped from 1.08 to 1.02, and there was no activity for a few days before we transferred it. For the dry hops, we put a marble and the hops in a mesh bag---it wasn't heavy enough so it's floating near the top. We added extra pre-boiled water to fill the 5 gal. carboy to the neck (that was recommended by the beer instructions).
Anyway---this morning, there is a lot of activity in the airlock---beer is in there and the entire thing is foaming (image attached). I'm scared about it exploding. Did we do something wrong--or is this normal? Should we have left more space in the carboy for this activity?
I don't have a blow-off tube, but if that's needed, will this beer hold up until tomorrow, when I can make it out to a store?