Ocean Acidification Instruments / Studies such as FOCE require a precision pH sensor capable of operating up to full ocean depth (4000m).

The Seabird SBE 18-I is presently used.    The problems found on FOCE and BRS:

1. The housing leaks
2. The sensor rails possibly due to physical placement near motors and either does not recover or takes 20 to 30 minutes to recover.
3. Seawater diffuses into the KCL electrolyte resulting in an offset over time.
   

Notes from Thom on possible solutions:

1. Improve the housing design
2. Redesign the sensor electronics and improve the grounding and isolation.    Provide an isolated digitized output.
3. (Possible Innovative idea) Use 'standardized' Seawater as the electrolyte to mitigate affects of prolonged exposure to seawater.    Preliminary reading about the chemistry of the sensor and a brief discussion with Ed Peltzer last wee (7/31) seemed to indicate this approach might work.
4.