Dear Customer,
I personally have not heard of any hot tubs that use such a reducer. Approx. 95% of hot tubs and spas use 2" piping throughout the tub and approx 5% use 1 1/2"
If this reducer union is indeed required, then unfortunately we will not be able to supply it to you. You may be able to pick up such a reducer from a local plumbing supply store or hardware store.
Sincerely
Peter Moroz
Office Manager
NLCT