As I understand it a "flush" is where you water your plants with 3x the amount of water as you have in pot volume....so a 3 gallon pot would be flushed with 9 gallons water. Is this accurate? And is it neccessary to do this? Can't you just stop feeding the plant nutes and use plain water for the last couple of weeks but water with normal amounts and let the medium flush over time or do you have to do a huge flush like I described above before harvesting? Thanks.