Bio monitoring needs to be performed during biologically matured period of a year to get fruitful results. In India due to tropical climate, monsoon occurs for a limited period (average rainy days are 40 in a year), but with high intensity. The entire biological system established during non-monsoon periods is flushes because of floods. After the monsoon recedes, the biological system starts reestablishment. After gradual succession, "mature" ecosystem established. This is the right time for biological sampling.

The sampling time for bio monitoring is preferably selected either in the morning or before the sunset because some of the benefit animals avoid extreme solar intensity and temperature, and seek refuge under the rocks in the interstitial sediments. For the measurement of functional biological parameters, such as photosynthesis and respiration, sampling is performed round the clock.