F,
In the old days of single speed pumps, a 3 HP pump would be way too much pump for most pools..
Today, the bigger the pump the better, in most cases.. This is because a VS pump is really variable HP pump.. You just adjust the HP of the pump to match your pool..
With a single speed pump, it was normal to only run the pump for the shortest amount of time possible.. With VS pumps, running 24/7 is now possible for the same cost as running a ceiling fan..
In my opinion, it makes no sense to to ever buy a 1.5 HP VS pump. You can always turn a large VS pump down, but you can't turn a small VS pump up..
Because the basic idea behind a VS pump is to run as slow as you can, and still get the job done, pipe size is no longer an issue, in most cases.
While many things were better in the "Good old days," pool pumps are not one of them..
Thanks,
Jim R.