We don't have enough experience with the AF200 yet to make authoritative statements, but the following is our current view:-

Sensor calibration. Only the RH sensor needs to be considered - the temperature sensors are sufficiently accurate and stable to contribute little to measurement errors. RH sensor calibration probably needs to be performed once only, when the instrument is new. Our sensors come with a specified calibration stability of <0.5% RH change per year, if kept clean. Biox use Klingon technology to protect these sensors from contamination, thus ensuring long-term stable and reliable performance. In any case, long-term sensor drifts can be compensated to some extent by the two calibrations below.

Baseline calibration. This needs to be performed every time you switch the instrument on, because of the hysteresis property of RH sensors. Baseline settling time depends on what the sensor has been exposed to since its last use, but it is much quicker with the AF200 than with previous AquaFlux models. 15-30 minutes is typical.

Flux density calibration. This needs to be performed at 3-6 month intervals using the the droplet method and the micro-syringe supplied with the instrument. The software handles all the calculations and you're done in less than an hour.