From other internet stories, I gather that swapping out a pool pump is pretty expensive, and I honestly wonder if that is the best approach. How about just putting your pump on a timer for some daily filtering, and getting in the habit of turning it on when the pool is being used ? The general problem with non-variable pumps is that they do more work than is necessary -- they are over-spec'd for the job.
I'm getting the variable speed pump installed this Friday. It's going to set me back ~$2,000. It's kind of crazy given that the existing pump is less than a year old. Even with a 50% reduction in energy usage (manufacturer says up to 90%, but I think that's optimistic), this thing will take years to pay for itself given the cheap price of electricity in Virginia.
That said, I honestly just can't stomach having a pool that consumes up to 1,500 kWh of electricity a month, more than anything else in my entire house. That just seems obscene. It also makes my solar aspirations seem futile - if I install a 7kW system, the entire solar array may be able to partially power my pool pump?!
I'll definitely share the energy usage comparison when we turn the pool up again this spring.