For future reference, this is what I do. I also have a 55G Reef tank, and I have multiple 1 gallon and 2.5 gallon containers with nothing but RO
water. On top of that I have a few 5 gallon containers with RO
water and two 7 gallon containers and two 6 gallon containers with saltwater. On top of that, I have 2 27gallon totes, 1 with RO
and the other with Saltwater, constantly mixing. Now, I'm not telling you to do what I do (as it may seem excessive) but it's good to have some backup water in case of a disastrous situation.