英国采购需求：二氧化碳计测试仪、二氧化氯比色计、氰化物环境pH电极、石墨电导率TDS电阻率盐度传感器、氧化还原电位计、水质pH监测系统

I'm reaching out to gather more information regarding the calibration frequency of digital sensors, specifically in the context of their use in water treatment applications. Understanding how often these sensors need recalibrating during sustained operation is crucial for our maintenance planning and overall system efficiency. Could you please provide insights on the best practices for maintaining these sensors? Additionally, any recommendations for optimal calibration intervals or factors that might affect this would be greatly appreciated. Thank you!