need advice on a ozonizer & ph controller

[cisco1717]

i have a pinpoint ph controller i've calibrated it but am just a little confused on the [set point] box with the "range" and "center value"
what value should i put on the high & low on both the range and center value.
also is there anyone who have a redsea ozonizer set up near queens that i can have a look at in person. i have one and i would like to set it up but i want to do right and carefully.
thanks.

 

[cisco1717]

any 1