This thread made my day Haha flush deezzz nuts haha. So in HYDRO with full synthetic nutes when running a high ppm program(1900-2300),and yes that's high af but can be done, with first feed on a 21 feed weekly cycle the first initial soaks will be more than enough to supply them with everything they need thus your res ex. initially at 100gal is now 70gal and then you can add more water that's the only time I'd ever consider anything I do flushing.....
WIth that said people who use the term flush generally are gana be using pgrs and being told that it scientifically makes their plants safe to smoke hahahaha. Flush Flush Fail hahaha