I have a 50 gallon aquarium that I use for a couple dozen tropical fish and 6 ADF's. I started it about a month ago with well water. I have the water tested regularly (I'm in PetSmart every few days anyway) and it has always tested perfect; except for pH... I think. I have a pH sensor in the tank which tells me that the pH is about 8.0; which according to the sensor, is high; but according to the literature that accompanies the PetSmart test, 8.0 is 'within normal range'...???? I'm really trying to do the right thing; I just can't figure out what that is.

1) What is an ideal pH for my tank?
2) What causes pH to go up? down? (I did read in this forum that well water could be the cause)
3) Should I do something to lower the pH?
4) If so, how?
5) If the pH in my tank is hurting my fish/frogs, how would it show?

HELP!