Pipe size and pump recommendation?

MNiels

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We survived recent major refurbishments to our 49-year- old pool and patio environs, which included replacing the entire screen enclosure, upgrading the deck with concrete pavers, resurfacing the pool interior (plus new tile, coping, and skimmer), and replacing the old DE filter with a cartridge filter. While everything looks great and the water is fabulous – thanks to TFP Pool School, Pool Math, and these forums! – we have some problems left to solve (if only I had discovered TFP earlier, might not have had any problems!)

Because of miscommunication with the paver installer, our pool equipment now sits below grade, plus the new deck drain brings a lot of water runoff into this area as well. When we get a good rain (and our Central Florida rainy season is coming up), the pool pump and motor will be flooded. DH and DS have a plan to elevate the pool equipment pad but that involves cutting the plumbing lines. We’ve been told that the diverter valve needs replacing, plus the pump is 11 years old and pump motor is 7 years old (and loud), so we are considering replacing them all together when we have everything disassembled for the elevation project.

But we may need to make some plumbing corrections, too. We have 2” pipes coming from the pool (one main drain, one skimmer) to the filter equipment. The pipes change to 1 ½” coming into the diverter valve. The pump has 1½” connections in and out (it’s a Pinnacle/Pentair PFII-P1-1.5 HP, with an A.O.Smith Centurion 1.5 HP/SF 1.10 motor). The pipes change back to 2” leaving the pump going to the filter (Pentair cartridge CC150). Pipes from filter back to the pool are also 2”.





First question: Is this plumbing arrangement OK, or should the 1½” plumbing be changed to 2”?

Second question: The pool equipment tech says we need a smaller pump and motor and is recommending ¾ HP. How do we figure out what we need? Any recommendations on type or brand?

Third question: The new cartridge filter (Pentair CC150) runs at a very low psi of 5. It’s been operational for 2 months now, and the psi is consistent; I clean it at 6 psi. We’ve had a DE filter for 35 years, so I’m not as familiar with a cartridge filter – is this an acceptable operating pressure for this type filter? Is the low pressure related to the plumbing arrangement?

Thanks for access to the wealth of knowledge and experience on this site, and for any recommendations! It's my first post and first time using Photobucket, hope it worked.
 
IMHO I'd leave it the way it is. There shouldn't be any problems with restriction with the 1.5" plumbing.
If you had 2" at the pump and filter it would be nice to have all 2" but for a 23K gal pool you should be fine with 1.5".

The tech says you need a smaller pump for what reason ??
If there isn't anything wrong with this one I'm not sure I'd buy a new one unless you wanted to go to a two speed or variable speed to save some money on operating expense.

The pressure shouldn't be related to your plumbing as your plumbing looks OK.
Usually it's recommended to clean when you have a 20-25% rise in pressure from your "clean" pressure reading. How dirty does it look at 6 psi ??
 
Thank you, husband is very happy with your response (less plumbing work for him)!

The tech just said the pump is oversized and recommended going with smaller one when this one dies, and possibly a VS, because the noise from this one is bothersome. The equipment pad is right next to the patio area, and it's impossible to have a conversation when the pump is running. I can hear it throughout the house, too, so it's a near-constant source of annoyance. Guess we'll evaluate options when it dies; husband liked your response on this point too!

I clean the filter at 6 psi because that's 20% over clean psi of 5 (or is my math wrong?). It looks dirty enough to me, but no prior experience with cartridge filters; however I will admit that there doesn't seem to be any filtration problem. Goal of course is to prevent problems... Does cleaning too soon or too often lead to problems (other than fatigue)?
 
Yes, it does fill up completely. There is a thin stream of very small air bubbles coming into the pump basket, which the pool tech thinks are coming from cracks in the diverter valve, which we plan to replace (or maybe just replace parts after disassembly and inspection). And we do seem to have adequate flow at the returns.
 
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