I'm thinking about dry hopping my current batch. It's still fermenting and bubbling, and the krausen hasn't dissipated yet. Should I wait for fermentation to stop? Should I wait for the krausen to fall out?
Yes, you should wait. The escaping CO2 will carry off the hop aroma you're trying to get through dry hopping. It's best to remove the beer from the yeast completely before dry hopping. There is an interaction between yeast and hops that can cause the hops to produce a very floral, rose-like ester which can be disagreeable.