I hate that eco earth. Its crap IMHO. It does hold humidity but it gets all over the snake because its tiny tiny pieces. One snake I had ended up with it in both its mouth and back end somehow. Tons of it. Not that this happens everytime but ya, I hate that stuff.
I would use cypress multch. It doesn't have to be wet for your king, but can be wet for your spotted. Just bake it first.