ok so we're looking for a hot tub or spa and i have some questions. just some info, we have an in ground pool and we want to put it behind the pool. fortunately we have the pool filters right next to where we want to put the the hot tub so it can easily plug into that. i really want the dimensions to be 5' x 6'. so first, should i get a hot tub or spa for behind the pool area? can i get a hot tub/spa for the size i want it or does it have to be custom made? and lastly, approximately how much will it be to install? thanks so much!!