I wouldn`t say it`s exactly wrong but it`s not right way either, kinda theirs more than one way to skin a cat sort of thing. But your looking to cause lockout from your grow medium of any left over ellements of your ferts, hence why no ph`ing, if plants just taking in water and hardly any left over ferts cus water is not ph`ed to optimal then in doing so this will clean plant out quicker where as by ph`ing the water if theirs any left over ferts in your pots they are gonna get used up before it starts to work flushing plants out, so it will priolly be a longer process not to mention that ph stuff int best stuff and are pretty potent chemicals/acids/whatever. But no mate knock that on head just straight up tap water. Looking and thinking about it, your prolly best ph`ing to summink stoopid like ph2.5 or 8.5 to cause full weight lockout of most if not all different ellements in your ferts if your gonna do that, but that`s just my theory and as said stick with plain water.
