Matt's the best source for this info! Check your dKH too - it is really more important than the PH. If memory serves me:

PH = 6.6 - 6.8
dKH = At least 30

It will take it 30+ days to settle in, check it daily. After you get all the flow rates correct, PH is a good quick check to verify the dKH is "probably" still good.