New tank 1st fill

[Jenner]

Just wondering how important using RODI water is when starting a new tank as I do not have a RODI system. I have a 55 gallon with a 25 gallon sump. Will have live rock / sand and some basic corals. I have a 14 gallon bio cube running now. Will be transferring everything from it once the new tank is stable. Only had the cube for around a year so I'm fairly new to the salt water game. Please help. I'm going to talk with the LFS tomorrow and see if they sell water.