u/Aressca

Found those 2 in my garden and they are much larger than the usual arianta arbustorum and grove snails that live here usually. Pic 3 shows one of them next to an arianta.
I live in northern germany

First time owning snails, I have had them for about a week now. The tank is about 50x30x20 cm. Since the snails are from my garden I gathered the substrate, plants, twigs and bark pieces from my garden as well. please tell me if this is fine for them and what needs to be changed! Also sorry for the quality, my phone camera is pretty bad.