your climate and trees and bather load are important missing pieces of
your puzzle.
in buffalo ny: our 12,000 gallon above ground uses a 2 speed pump so
you can vacuum or open your season with plenty of water flow and
turnover of the chlorine shock level.
depending on how you skim the pool's surface a pump that's too small
won't suck enough to skim.
we use the low speed more in cooler weather with less bather load. the
high speed is good thru summer with high bather load and to catch the
falling spring seeds and early autumn leaves from the trees before they
sink to the bottom. swimming season begins in may is over on september
labor day and we cover the pool before the leaves start falling.
here's a good site:
http://www.haywardnet.com/pdfs/Pump_filter_sizing.pdf
and:
http://www.haywardnet.com/inground/products/
general info:
http://en.wikipedia.org/wiki/Swimming_pool
energy saving stuff that doesn't work for us at:
http://www.eere.energy.gov/consumer/.../mytopic=13290

Wes wrote:
I need to replace my pool pump as the bearing are gone and I am leary
of previous cavitation trouble. I have been to three different pool
stores and have been given three different recommendations. Now I want
the real answer, not just what they are trying to sell me.

Specs:

20,000 gal pool
Pool/Spa combo with 4 spa jets
2" PVC supply lines
2" PVC return lines
Pump - currently a Pentair Whisperflo 1HP Full-rated 115/208-230 volt
(original equip from 1986)
Filter - Jandy CL460 Cartridge
Heater - Raypak RP2100 Natural Gas
Cleaner - Suction side Kreepy Krauler type
Equipment is located about 40 feet from the skimmer
Need to have a pump that is as quiet as possible as it is located right
under a window of our house.

Advice so far:

1. Replace only pump MOTOR and seal with same exact single speed 1 HP
Whisperflo motor. (Was told least expensive and all that needed to be
done)

2. Replace entire pump with single speed 3/4 HP Full-rated Pentair
Whisperflo.
(Was told the larger pump size causes cavitation and is louder, and
that 3/4 is plenty strong enough for spa jets)

3. Replace entire pump with 1.5 HP Full-rated Pentair Whisperflo.
(Was told needed larger pump to match large filter size and decrease
circulation time)

4. Replace entire pump with 1 HP dual speed Pentair Whisperflo.
(Was told it is the quietest ,most energy efficient, but more likely to
malfunction early and much more expensive)

Questions:

1. Is filter oversized? It is brand new, put in by the pool company
that replastered.
2. Which option above is best for this pool? Or other option even
better?

Thanks!

Wes