I'm in Edmonton and a month ago set up a 10g using tapwater and Prime. Even though the rock is still curing, I do weekly water changes, making sure to siphon out the crud that accumulates on the tank bottom. I top up with old-fashioned kalk mixed with RO water purchased from Zellers. Mainly softies will go in this tank, though I might try sneaking in a BTA. The light fixture that came with the tank kit holds a pair of household daylight compact fluorescents which, I believe, emit the equivelant of 120 watts of conventional light.
When I was in the hobby a few years back, I used nothing but RO/DI in our tanks ranging in size from 28g to 180g and felt I was doing the right thing. With this 10g, though, I wanted to go very low tech with low startup and operating costs. As I don't have a lot of experience using tapwater in a reef, I don't feel qualified to direct you toward one path more than the other.
You can find out more about Edmonton's water at
Epcor Water Quality Reports.
According to this
Water Hardness Scale, Edmonton's water appears to be on the border between soft and slightly hard.
HTH
