Chris is so right. My sister had just put in a new pool when I got my tub. Since we went to my dealer with me several times, she asked if he had pool chemicals because she would definately buy from him (and I would too). So from that one spa sale he would have also made 2 pool chemical customers.
I try to buy all of my chemicals from my dealer (although he is quite a distance from me). But sometimes if I am at the pool store and I need something for the spa, I will just pick it up...So it is definatly a good idea to carry both pool and spa supplies.