Tortoises store D3 in their bodies for later use. There are many variables at work, but any normal tortoise can go several weeks with no UV at all, and in some cases they can go more than 6 months. Adding D3 to the diet or with a calcium supplement can extend that time substantially and possibly indefinitely.Actually I don't want to use a uvb lamp, However, this week and last week, the sun rarely appears so they only get sun 3 times a week, but I still soak them every day. I'm afraid they will get mbd so I want to buy a uvb lamp. But I give them pellets containing calcium d3 for their shells, can that help? and I soak them by dripping hydrobozz in the soak
This being the case, they do not need hours of UV every day. Just a couple of hours a week, with no D3 supplementation in the diet, will prevent MBD completely. Skipping UV for a couple of weeks now and then due to bad weather or a busy work schedule will do no harm whatsoever, and there will be no hint of any MBD. With some D3 supplementation, these time frames can be extended even further. To bring about MBD in a tortoise, they have to go for many months indoors with a poor diet, no calcium or D3 supplementation, and no indoor UVB source. Even brief amounts of time outdoors once a month will stave off MBD for a long time. Years in some cases.
Most people in warm sunny climates do not need indoor UV, and can easily get by without it. If you live in a cold northern climate, then UV indoors is essential.
What is hydrobozz? We don't have that here, and I'm coming up empty on an internet search.