Daylighting systems with flexible tubes simply do not perform well. Flexible tube by its very nature is not a reliable means of transferring light; light entering a flexible tube will not necessarily continue to bounce on a downward path, but will scatter randomly in all directions (including upwards) as it bounces off the concertinaed surface of the tube. Such systems are usually of poor quality and light output from flexible tube products is vastly inferior to that of a rigid tube system, indeed we are often asked to replace them with our Daylighting Systems. See the example below where one Solatube Daylighting System replaced two flexible duct systems.
Independent test results have shown that Spectralight Infinity tube material will deliver 10 times more daylight than a flexible system.
In the image below, one high quality Solatube Daylighting System replaces two flexible duct systems.