I can use my live rock frkmmy old tank .which 3 years old . But cant use the sand .since I'm using a different sand for the new build .Everyone has their own way of doing things listen to everyone and the go from there and develop a system that works for you and your tank
Do you think it would be helpfull if I take the new sand place it in a cup in my old tank for few week for the bacteria To get init and place it in the new tank .