D3 adjustment based on UVB strength: How Bearded Dragons Use It
Frequency
Reduce dietary D3 as UVB output increases
Role
Bearded dragons are strongly diurnal, high-UV baskers in the wild and have a real physiological need for UVB — this isn't optional the way it can be for more nocturnal species. With a proper 10.0 or 12% T5 HO tube run correctly, the dragon synthesises most of its D3 through the skin, so dietary D3 dosing should be lighter than for a UVB-free setup. Consult a reptile vet for exact reduction amounts.
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Calcium powder without D3 is used every insect feeding, and lightly dusted on the daily salad. The primary defence against Metabolic Bone Disease, which remains the most common serious health problem in captive bearded dragons.
Calcium powder with D3 is used 2x per week if using adequate uvb; consult a vet on dosing if not running uvb. Supports D3 synthesis and calcium absorption alongside dietary intake.
Multivitamin powder is used once per week. Provides vitamins and trace minerals not fully covered by gut-loaded insects and fresh produce alone.