The 10 watt halogen bulb in the biOrb light unit should last for around 1200 hours. We recommend leaving the light on for 6-7 hours a day.
The biOrb bulb must be replaced with the correct biOrf 10 watt 12 volt bulb. Larger bulbs may kill the transformer and could have an adverse effect on the light unit and biOrb. sku 82278000205