I have a 13.7K gallon above ground pool with 1HP pump, and I'm looking to lower my operating costs. I posted earlier looking for more conventional replacement-pump advice; this post is about an "unconventional" idea that I'd appreciate some sanity checking on.
The key cost-lowering factor "everyone" seems to agree on is running the filtration system at a far lower flow rate for more hours. The conventional way to achieve this seems to be to replace the pump with a multispeed pump that can be run very slowly (as well as at "standard" speed). But these multispeed pumps tend to be rather expensive and include fairly expensive control electronics, some of which cannot be replaced separately.
With this in mind, I was wondering if plumbing a low capacity energy efficient pump like http://www.bestpondpumps.com/waterway.htm (45 GPM @ 1.3A claimed) "in parallel" with my existing 1HP pump, with check valves added to the discharge lines of each of the pumps, would do "about as good of a job" as a multi-speed pump. Yes, the extra plumbing would cost extra $$ ($45 for check valves alone!) and add a small amount of piping loss, and I'd have to wire up a 2-motor "controller" (switches/relays) that would activate the pumps as needed, but these are within the capability of a DIY'er. And avoiding a system with an expensive point of failure would be a benefit. Also I could upgrade the 1HP pump with a more efficient one when I saw fit.