welcome to AA You found the place to get the right answers .
I have started cycling the tank with premixed saltwater from the store. I was told by the store I only need to cycle this for about a week before I added sand and live rock. Its a Biocube 29.
let me ask this why would you cycle just water that's just a waist of time,
add water than rock and sand than add a deli shrimp in a old stocking and let your cycle begin,
if you bring your questions down to the saltwater section you will get all the info to start your tank correctly