how does a PH controller work??

[rickkott13]

hey guys. i have couple question though someone could give me a clue how does ph controller works? i can manually adjust it up and down?? do i put the ph probe in my ca reactor or sump? thanks in advance

 

[rickkott13]

oh also how does it work if you adjust it up and down> ? any other equip i need to get>? i have ca reactor and kalk for topoff

 

[rickkott13]

ne1?