It is well water, with a pH of 6.7 and ~50ppm tds. I don't have a favorite pH, but when the plants don't look happy, I use a bluelab soil pen as an indicator that something is wrong. Usually around 6.3-6.5 when everything is hunky dory. It's all in a pre- flushed coco, perlite, and worm casting mix 7:2:1 respectively, amended with Espoma Garden Tone (3-4-4) and EcoScraps (5-5-5). I use about 2/3 of 1/3c (really 2/9c) Espoma and the remaining third (1/9c) EcoScraps, for a total of 1/3c per 5 gallons of media. Sorry it's pretty specific, but it does indeed work when incorporating a routine flush. Just wondering why I have to... Seems like there's always a ghost in the machine with organic chemistry. Fascinating though!