Terrapin tanks can soon become very smelly and salmonella is always a danger, so good hygiene is extremely important for terrapin care.
Water in terrapin tanks should be changed frequently. Even with a good filtration system in place, it is essential to change the water, or at least some of the water, two or three times a week. Filters also need to be kept clean and free from waste products.
Terrapin food should never be allowed to stay in the water and left to decompose. It is a good idea to have two separate terrapin tanks, so that one of them can be used just for feeding and cleaned out between feeds. The other tank can then be cleaned during feeding times.