kelp and seaweed

okay so i just purchased some kelp and seaweed and im just wondering what exactly they do. i mean i know they make the plant thicken up and give you heavy buds but im just wondering if anyone can cleariffy all of it for me.

thanx.

oh and for my nutes im using all age old products with dutch master potassium and unsulpherated molassis.

any constructive critisism welcome.