In general do you need to use the pool casing, it is a pipe leading to the pool channel. But ordinary casing is difficult to seal, and thus there will be between the casing and the pipe from leaking between the casing and the wall is also easy to leak. Only words with a waterproof casing and the wall of casing solution leakage between, it can not solve the seal between the casing and the pipe, flexible waterproof casing both of these problems can be solved exactly. In general do you need to use the pool casing, it is a pipe leading to the pool channel. But ordinary casing is difficult to seal, and thus there will be between the casing and the pipe from leaking between the casing and the wall is also easy to leak. Only words with a waterproof casing and the wall of casing solution leakage between, it can not solve the seal between the casing and the pipe, flexible waterproof casing both of these problems can be solved exactly.