How often should I replace the HR96 reflector of the Hortistar?

Miro Aluminum reflectors don't oxidize quickly, but they get dirty by dust and deposits that are almost impossible to remove without damaging the reflective material. Calcium deposits (from damp and water), pesticides and sulfur are common deposits. Depending on how clean you work we recommend to change the reflectors once every 1 to 2 years. That can save you up to 10 % reflected light.