A thought with regard to the Paphs... I don't know what minerals are in your tap water. But in several talks by Brandon Tam, who oversees the orchid collections at the Huntington Library, Art Galleries and Botanical Gardens, he has mentioned that they have found that their world-class Paph collection actually does better with the local well water (high calcium, ranges from 200-800 ppm TDS, pH around 8) than with RO. They use RO for most of their orchids, but the Paphs seem to thrive on the hard water. Phrags are a different story, they prefer RO.