It IS possible to overdose on calcium. Giving loads of calcium every day will eventually result in a lack of other important trace elements and nutrients. Likewise, using human pills for D3 could result in an over dose. Everything in moderation...Thank you for your advice! I will be using the repticalc with D3 2-3 times a week during the colder months, since he is now eating grocery store greens.
You are right, I am probably overthinking it. I just got a bit scared from all the articles stating how dangerous it is to overdose on calcium and especially D3 if given orally. You are probably right, that I am on the safe side with those things
Using a small pinch of calcium powder with D3 in it that is intended for reptiles two or three times a week is enough to meet your tortoises needs and cannot result in an overdose. And as I said before, there is a very wide margin of error on this. You could do double this or half of this, and your tortoise would still be fine. There are people with healthy tortoises out in the world that use calcium every day, and others that use no calcium supplementation at all. For most of each year, I use almost no calcium supplementation on any of my adults. This is because I feed them an abundance of weeds that are high in calcium, along with regular feedings of opuntia pads and mulberry leaves, both of which a very high in calcium content. In fall, when the weeds have all been long dead and dried up, the mulberry leaves all die and fall off, and my cactus stand go dormant, I rely on grocery store lettuce, endive or escarole, bought by the case. I add calcium powder to the lettuce, as well as soaked horse hay pellets for fiber, and dried leaf options for variety. During that time of year, I also feed them occasional Mazuri to make sure their nutritional needs are met until the rains return and bring back the wild weeds and grasses for them to graze on all winter. Our winters are warm and sunny here. Daytime high temps are around 20-24C and mostly sunny with occasional rainy days to water the weeds.
All of the above is an attempt to explain why the advice varies so much. Some people live in cold areas where the tortoises are indoors and there are no weeds to scavenge due to several feet of snow on the ground. These people usually rely on grocery store lettuce and need more calcium supplementation in their tortoise's diet. On the other end of that spectrum are people in warm tropical climates whose tortoises live outdoors and graze on calcium rich leaves and weeds year round. These people don't need any calcium supplementation at all. I'm in the middle of those two extremes, so I only need calcium supplementation for a small portion of each year. I use more calcium for growing babies of giant species, and I use little to no calcium for grown adults of small species. How much calcium to use varies a lot, but a small pinch twice a week is a good general guideline and will serve most tortoises in most situations very well.