4. For 4 port cable assemblies, refill the calibration cup with fresh calibration standard to approximately the first line for pH, ORP, and turbidity calibration. Fill to the second line for conductivity calibration (Figure 43 on page 34). If using the ODO/CT cable assembly and calibrating conductivity, ensure the vent holes at the top of the sensor are completely immersed and the solution level is at least 1/2 inch higher than these top vent holes (Figure 46 on page 36). A cylinder is included with ODO/CT cable assemblies for the purpose of calibrating conductivity