When reusing a yeast cake is it better to dump the cooled wort on top of the cake or rack on to the cake? I only ask beacuse I brewed a pale ale last night and dump it on to a notty yeast cake from a previous pale ale brew. I thought by dumping it on to the cake that it would add oxygen and have a good start for fermentation. That was 12 hours ago and still no activivty. What should I do?