The fluorescent reader gain setting determines the amplification of the incoming fluorescent signal. It is important to use gain settings in the correct ranges. Gain set too low will not capture as much signal as possible, leading to poorer quality data. Gain set too high will saturate the reader leading to meaningless results, which are not always easy to spot and can therefore lead to incorrect data. We advise first running a test with the reader set for optimised gain, and then use the values suggested by the reader.