Hi Al,Al G. said:mattseattle posted on Reefcentral that Seattle's water was <35 TDS, which is really good. I know bufford in Tacoma uses tap water and now know that Ray in Blaine uses tap water. I guessing at least in some western WA locations, tap water is pretty good.
My first attempt at a reef tank in 1998 was with tap water and it was algae heaven. My current tanks use store bought RO/DI, which works great. I plan on getting a home RO/DI soon, though I'm tempted to start a 10g tank using only tap water and see what happens.