You don't ph until after you add nutes, right? Regarding aerating to disipate chlorine: 1) you have to know whether your municipality uses chlorine or chloramine. Many (most?) use the later which doesn't aerate out. 2) Water supplies are closed systems. The amount of sanitizer added isn't much. Spitting in your water or adding sugar (anything to spur some bacterial growth) will exhaust that sanitizer. If you grow in dirt, it will probably be exhausted upon hitting the dirt. They don't put enough in the water to sanitize dirty areas.