I've been using tap water in my sps dominant tank for 15 years which has a heavy bioload of fish. Nitrates average 15ppm and Phosphate around .1 with the use of vodka and lanthanum. I get that people believe rodi is the only way but I do question how many of them actually have tried a window and compared results.
Tim helped me set up my Apex and we had many laughs over his bad water. I think we have shared killing many acros together. He was one friend I'll remember in my life and I was blessed to have met such a genuine soul. God bless you my friend.