Adding EE to my tank

I just got 3 big bricks of EE and i really want to add it to my tank .Right now i have play sand in all of it but ireally want to change things around and try new things in the tank..... But ....... I have never used this b-4 should i put all the tank with EE or should i mix it with the sand or half and half????? my crabs r happy with just the sand and if I want to do a change over now is the time b-4 winter hits and I can't get my 40 gall tank outside to clean.
I have not changed the sand in over a year and i have not lost no crabs so.... i'm kinda scared on what might happen PLEASE HELP

 

You can mix the EE in with about 1/3 of the sand and see if your crabs like it.If they seem to take a liking to it,you can replace half of the sand with just EE.I hear that exotics love that stuff.