PSI Dropped to 6 from 10 after Pool Revamp

EllieWilliams

Platinum Supporter
LifeTime Supporter
Oct 28, 2012
108
Houston TX 77064
Weirdest question I think I have ever presented to you all -

Just finished a revamp on my 40 year old pool - new cooping, tile and surfacing (drain hole plugged). Replaced pump and motor for prosperity, as well. Cleaned and replaced the filters. Everything is clean, clear and running really well, inlet valves are pushing water with no air - so I am scratching my head and thinking how can my filter psi be only 6 when it has been running 9 for years - could the revamp have brought the old gal back to a new norm?

1) for the last 10 years running at a consistent 9-10 psi - now 6 psi
2) new revamp gave me chip out and brand new inlet valves
3) troubleshot all the causes for low psi - water level perfect, clogs in skimmer, piping, etc, double checked all the connections, 0-Rings replaced with pump (but double checked), etc. - but nothing is a problem (assuming gauge is still working)
4) history of plumbing: a) replaced skimmer 5 years ago; inlet valve leaks 7 years ago resolved; motor replaced 10 years ago (prior to this new one)

Pool is 75 feet perimeter, 4 inlet valves, 1 skimmer, with 1-1/2 in PVC piping and only a 1 HP pump and filter connections (see pic), pretty simple.

Thoughts
 

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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,405
Laughlin, NV
Same exact pump? Or did you just replace the motor? Does the gauge go to zero when the pump is off? Does tapping the gauge do anything?
 

borjis

LifeTime Supporter
Aug 19, 2014
3,008
Pacific NW
That is a bit odd.

I had a few psi rise going from a Jandy 250k btu heater to a Raypak 266k btu heater.
Which was sort of half expected.
 

setsailsoon

LifeTime Supporter
TFP Guide
Oct 25, 2015
1,572
Stuart/FL
Brand new filer cartridges? That's a lot for new cartridges though. My guess is that even though the pump and motor are duplicates maybe the pump has been improved somewhat and you now have a different performance curve or you had damage internal to the old pump and didn't know it.
 

EllieWilliams

Platinum Supporter
LifeTime Supporter
Oct 28, 2012
108
Houston TX 77064
That is a bit odd.

I had a few psi rise going from a Jandy 250k btu heater to a Raypak 266k btu heater.
Which was sort of half expected.
And the pool plaster stated that it is not the first time that an operating system dropped in PSI, especially on the older pools with all original innards. Could it be that by closing the drain (the skimmer was replaced due to the drain connection there disconnected and caused a major leak, so it was closed at skimmer) and replacing the inlets may have tightened up everything to cause less friction?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,405
Laughlin, NV
Most likely due to a number of factors. More efficient plumbing, slightly different pump curve, etc.

I do not think it is anything to be concerned over.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,462
Bedford, TX
Ellie,

Just so that we are all on the same page... Low filter pressure is better than a higher filter pressure as long as the water flowing back to your pool is the same.

Filter pressure is the amount of effort it takes for the pump to force the water through the filter and plumbing... The less the filter pressure the more flow you will have.

I have a VS pump that I run at about 1200 RPM and my filter pressure is only 1 or 2 lbs. and my pool works just fine.

I think that you are worrying over nothing..

Thanks,

Jim R.
 
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EllieWilliams

Platinum Supporter
LifeTime Supporter
Oct 28, 2012
108
Houston TX 77064
Brand new filer cartridges? That's a lot for new cartridges though. My guess is that even though the pump and motor are duplicates maybe the pump has been improved somewhat and you now have a different performance curve or you had damage internal to the old pump and didn't know it.
Oh, no, nothing changed on the filter same one, just changed out the filters themselves to start with a clean slate, it is solid as a rock. Filter: Pac-Fab (Pentair) Mytilus MA-90C Cartridge;
 

EllieWilliams

Platinum Supporter
LifeTime Supporter
Oct 28, 2012
108
Houston TX 77064
Ellie,

Just so that we are all on the same page... Low filter pressure is better than a higher filter pressure as long as the water flowing back to your pool is the same.

Filter pressure is the amount of effort it takes for the pump to force the water through the filter and plumbing... The less the filter pressure the more flow you will have.

I have a VS pump that I run at about 1200 RPM and my filter pressure is only 1 or 2 lbs. and my pool works just fine.

I think that you are worrying over nothing..

Thanks,

Jim R.
Jim, this is the best thing I could hear, as I am sure subconsciously I had come to the same conclusion days ago. It is so hard to see something new when everything was so different for so long. I believe I have over thought the new pool process and my system. I shall let the process complete and enjoy my new (used) pool.

Thank you all for your input and reassurance to the thought process, makes me sure I am coming to the same conclusion. Have a wonderful Easter and enjoy.
Ellie