which type pH sensor can be used to interface with the NI DAQ 9178 with module NI 9225?

[CUTEE]

WE  ARE  DOING  A  PROJECT ON   AQUACULTURE. WE ARE USING  NI DAQ 9178, NI 9225/9, NI9263. WE WOULD  LIKE TO INTERFACE  pH  SENSOR  WITH THESE MODULES.CAN  YOU PLEASE  SUGGEST WHICH TYPE  OF pH SENSOR AND WHERE SUCH pH SENSOR IS AVAILABLE (INDIA).