Yes...because Kent is using concrete, block..etc. for structure (strength) and liner for sealant. Never expectant liner to be structure (hold back dirt or water pressure).
Sure liner is probably lower INITIAL cost. But when you have replaced it in X years....and maybe would not have to do that with fiberglass or polyurea or CIM......maybe it will be more expensive in the long run.
Personally I would never buiild a koi pond for the long haul with liner as the sealant. Personally I want to learn enough about fiberglassing to use it on a pond. Our koi cousins in the UK do that all the time.
