it would be easier and better for resale value if you put the pond outside and glass it in like a sun room add on then you can use live plants in there to and see it from the living room and still have room in the garage. if your set on the garage you will need to get a permit and have it inspected it would be like a pool not like an outdoor pond with a liner wich alot of areas require a permit to install good luck and post some pics that would be awsome