Quote Originally Posted by aylad View Post
...you can put a smaller motor on it and save...
I'm sorry to contradict, but...
You'll need a motor that can supply enough power for the impeller. So stick with a motor with at least the same HP rating (or at least the same HP x Service Factor) unless you change the impeller as well.
You can, and I'd recommend it, buy a two speed motor and only run the low speed. This will save energy and give you better filtration, downside is suction for skimming and vacuuming is less and the two speed motor will cost more.