A good start there. They need to be fed with feeds as well. There is a formula to aid their growth and shelling. Always remove leftover meals from the pen house. Snails are clean animals.
The sand should be heated to kill all microbes to prevent the snails from attack. The sand is changed regularly too. My little contribution, wishing you all the best @gallantmayor
RE: Starting my heliculture business(Snail Rearing business)