hello my name is tim.I am searching for a new calcium to give to my tortoise i recently discovered that the calcium ive been offering to clark has no vitamin d and this concerns me.If anybody can recomend a good calcuim or a site to order from i would be much appreciated.aslo i was wondering how often do u offer calcium to a spur thigh i offer clark a dusting of calcium 3 to 4 times a week every other day in a meal.the calcium ive been using is called rep-cal herptivite with beta carotene multivitamins.ur comments and advise would be much appreciated thank u