I like to use apple cider vinegar to ph down and I like to get it low (like rain) ph of 5.6 to 5.8,,,,this stops nute uptake and growth until the ph buffers back up but the flush removes most of the nutes so it's all good
But for me that is how I water for the whole grow and I feed till the end
you can flush the nutes from the soil but not the plant