The flushing is a grey area but the theroy behind the reason is to STOP the nutrients that are avaible from being used by the plant, RIGHT? If the PH is very high/low the plant wont be able to use any of the nutes at the root zone. Isn't that why growers flush? So by having the PH out of wack would give you exactly what you desire. I flush every other day for the final 10 days with the PH of 8.5 ( my tap water) I have had years of over exceptional harvests.