When boiling crawfish and crabs, you taste your boil and you want the water to taste a little bit spicer and saltier. When boiling shrimp you want your water to tastes the same as you want your shrimp to finish. Adding potatoes and boiling them first (preboiling) depending on the amount of them will soak up some of your seasoning. Not a big difference tho. All in all there is 100 different ways and recipes and they come out great. You need a system and boiling rates are different w different burners.