I've been dealing with this pump issue off and on for over a year. Most recently the customer had his pool renovated and the pump/filter was moved maybe 10 feet from it's previous location. Before the equipment was ever moved the owner always had issues priming the pump as well as always had a large air bubble when it was running. It never seemed to fill all the way up. I have been over the pump 100's of times and never found any air leak on the suction side of things. Pressure tests on lines show no leaks wither. This is a rather old pump, Ultra-Flow, of which parts seem to be getting scarce. I've replaced lid o-ring, drain plug, seal plates, the works. Now that the equipment was moved and the issue still remains I am leaning towards just replacing the old pump all together. I believe it is a 1 1/2HP motor but not 100% sure as the label is not readable any more.
The pool is about 12,000 gallons. All of the lines except for the spa drain are 1 1/2". Spa drain is a 2". Pool has 2 returns, one drain, and one skimmer. Spa has one drain, one return and several jets. The owner is also contemplating adding solar to the pool . Single story house. My estimate is another 1 1/2HP pump should be just fine and probably a 2-speed one at that although there are still plenty of single speeds available to the homeowner. Since he just spent a ton of cash on the pool and a new outdoor kitchen he might not like the higher priced 2-speed motor.
So a 1 1/2 should be ok for this setup from my calculations, in other words just looking at it. Oh yeah the filter is a Hayward 120SQ put in by the builder 10 years ago.
Are there any other considerations I should look at?