Just brewed my first all grain Porter yesterday. 5gal Igloo cooler with a false bottom built at my local home brew store. went to mash out and not a drop. One call to my beer brew mentor, and he had the solution. I blew in the drip hose while my kids stired the mash. bingo we had flowage. I found you do not need to blow very hard or mash will fly out the top.