Hello there!

Hello I just purchased a 90 gallon reef ready tank with light sump and RODI filter. About ten years ago I had a 20 gallon saltwater and was doing it all wrong. I am looking to have a mixed reef tank. I want to get started but for the life of me I do not know how I am going to use the RODI filter to get 90 gallons of water in my tank. If I put it a container...how do I get a gazillion pounds of water to my tank? What process did you guys use when initially filling up....thanks