This is a very interesting topic. I would not be surprised to learn that there has been little to no study on the most energy efficient way to run/clean pool filters. And as you guys have determined, of all the things that contribute to pump losses, all of them like pool piping, pump size, etc all stay the same, whereas the filter losses increase as debris loading increases.
I understand that Dan1000 is able to determine motor kw usage by means of the Intelliflo pump diagnostic display, but how is mas985 determining the motor kw usage?
Pentair publishes energy consumption as a function of RPM level which I modeled. Chemgeek did this as well.
Also, as another data point for cartridge filter sizing vs pool size, I have 420 sq. ft. of cartridge filters for a 24,000 gal inground pool.
It is fairly easy to determine the amp draw of the filter pump, but unfortunately, this amp draw is composed of both "real" and "reactive" current, and the utility only charges residential users for the "real" current. Only the "real" part of the current contributes to the kw usage of the motor and kw is only what the utility charges. As an aside, utilities make a very big deal of charging commercial and industrial customers for the "reactive" current.
The electric meter on the side of your house is the most accurate you can get since that is what the power company actually charges you by. It is a bit tricky to remove the other stuff in the house but if you don't mind reseting a few clocks then the best thing to do is turn off all the breakers except the pool.
It would not surprise me to learn that the majority of filter debris loading occurs after only a couple of weeks or so. I have been following the "tried and true" adage of cleaning the filter after the psi rises 10 psi over a clean filter, and, for me, this takes roughly 8-11 months. I have a big hunch that the "clean after 10 psi rise" rule is leading to a bunch of wasted energy.
That's one reason why I never wait that long. In fact I usually clean it before a 1 PSI rise but we are getting a lot of ash from nearby fires so I am waiting for that to clear up.
And if the answer to saving energy is an increased frequency of filter cleaning, then it would be very useful to come up with ways to make this unenjoyable task 1) quicker, and 2) less messy. This increased frequency of filter cleaning might make devices such as this finally worth the investment,
http://www.neoterics.com/
I clean mine twice a year and for the most part it isn't that hard or take that long, maybe a half hour.
Also, there is a cartridge filter out there that claims to be able to go longer between cleanings because of a special flow pattern that somehow enables the filter material to be more evenly loaded. Unfortunately, I can not find the link where I saw this information, but I thought it was Sta-Rite?
Titanium