No easy way to test it with tap water, Plus getting large amounts of water out of the tank would not be too easy. I also still need to get some sort of mixing container for making more salt water but figured the first time it could be done in the tank since it would not have anything.
Hell I could fill it up a good part of the way get it to temp and put wave makers in and mix the water in the tank before live rock and sand went in. Of course, leaving enough room for the sand and rock.