You want the roots to grow into the water.. 6.1/6.2..to me.. it's within range.. as long add it doesn't get much higher than that.. but it sounds like your there to ph then back when you need to..
I was checking mine about every 24 hours.. mine didn't have any problems.. as long as you ph it back down.. you should be good to go.. after a week.. it should stay in the 5.7 range with in 24 hours.. again that's what my setup did is doing now..