Hi! You want to dust at every feeding with a phosphorus free calcium without D3, except one feeding per week. That one feeding you’ll use your calcium with D3 one week and a multivitamin without D3 the next, alternating so each is once every other week.I have a Male Veiled Chameleon 1year & 2 months old. How often must I dust the Roaches I feed him? Is it every day or once a week? I also have D3 Calcium which I use once every 2 weeks.