I don't know what you mean by max rated and nominal rated .......... but I have a 24ftAG and I have a full-rated 1/2hp inground pump on my pool and it is plenty. My old pump was a 1hp but when I replaced I went with this other one. (Poconos advised me on what to buy and he knows pumps way better than I do.) People tend to go with bigger is better but on a pool, bigger is not better when it comes to pumps. A pump that is too big will blow dirt right through the filter.

I'm going to let one of the resident pump experts chime in here .................