Re: double and tripple vortex
Ew. I think that would be kind of gross unless MaybE you had the same flavor in each bowl cuz after one bowl is cashed out then youd be sucking in the air of the smoked out bowl. If your gonna take the time to clear out the burned shisha (which seems highly recommendable) in the just smoked bowl, then you might as well just pack three separate bowls and have them ready to go to begin with. Plus youd have to refoil the first and second bowls any way since excessive airflow from the other bowl would be a problem.
bottom line: stick with single headers.