Here I am getting ready to dry hop and rack off into secondary. The reason I’m doing this is because I would like to keep the yeast cake at the bottom of the fermenter. If you dry hop directly in your primary, it is not recommended to re-use the yeast cake as the hop oils will coat the yeast cells and make them ineffective. So to avoid all this trouble, I’m just going to rack off to a secondary fermenter.
Now what you CAN do is what many of the breweries do: start a NEW batch of wort and simply siphon it into this ‘used’ fermenter. You have to be sure of your sanitation though and that your yeast performed well. Also you need to empty out some of the yeast cake..