So I have a batch of cider that I am fermenting using wild yeast (it's my little experiment) and have build a fairly large yeast cake at the bottm of my 1.5 liter bottle. Now it's been fermenting for nearly a week now and I'm getting ready to lay down another round of fresh juice on top of it. I'm getting ready to cold crash, my question is can I use a cooler full of ice to do the job for me or will it make the yeast too cold and kill them off?