Which week does the automatic flush start?

You only need a few days to flush in DWC.. week max if you are hoping to see some fade. Granted these are autos and autos are weird so I’m not sure you’ll get the fade like a normal photo. Anyhow 3-5 days max. First day I usually run a flushing agent like florakleen in there for an hour, then drain completely.. Fill with pH’d water. Let that run for a day Day 2 Again add a bit of florakleen and let circulate for an hour.. drain and fill with pH’d water again and that usually will have me very close to my input water EC/PPM of 100PPM or .2 EC Then let that be until you chop. Whether it be another day or more. You can do this without a flushing agent as well or just with a single change out. This is just what I do