Howdy....we do this all the time for folks....
best way it to get the tank all set up and flowing..with all your existing rock/sand........for at least a week, then you can safely add The Package with no issues.....just keep on top of the water quality....and you will be fine.....most folks never have to change any water....but each tank will vary....
when ready use the online order form!
sea ya
Richard TBS
www.tbsaltwater.com