Polaris 280 has a 3/4HP booster pump that runs continuously when the cleaner is operating. Usually, it's tied to a timer since it doesn't need to run 24/7. Electrical usage should be around 1KWH -- that's around $0.10/hr in many places. If you run the pump 4 hours per day, that would be about $12/month.

And, using a Polaris 280 does not require you to upsize the pump in the slightest.