I'm not sure what the nutritional facts of calcium for OHPW are, but you don't need to add any calcium to the recipe. I believe that the HPW powder has all of the vitamins and stuff that the gliders need.
I used to feed TPG, but switched to OHPW. My gliders like it so much better and I feel like it does a better job of balancing the amount of calcium/vitamines that they actually get.