A lighting system is provided that is configured for use with one or more hydroponic towers. The primary component of the lighting system is a light tube that includes one or more LED boards affixed to a central, actively cooled, mounting fixture. The LED boards may be affixed to one side or to multiple sides of the mounting fixture. A tethering system locates each light tube within the hydroponic farming facility, the tethering system configured to (i) allow for thermal expansion and contraction of the light tube, (ii) maintain the desired location of the light tube, (iii) simplify removal of the light tube, (iv) prevent accidental disengagement from the top mounting fixture while still allowing limited movement of the light tube, and (v) allow disengagement from the bottom mounting fixture when undue stress is applied to the light tube.