I use both of these supplements myself for both my gray tree frog and dart frogs. I dust with calcium one day, vitamins one day, and then an off day, and repeat that cycle. I've read that it can actually limit the effectiveness of the calcium/vitamins to use them together, so that is why I alternate. I'm sure others can chime in as to whether or not that is the right way to do it, but that's how I do it.