Skimmer Suction Air Leak - Hypothetical?

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Is the return side about the same?

What is the Matrix model#?

Is the plumbing all 2"?

What is the filter pressure?
 
The return side is much longer. After the filter about 85-95 ft total.

Matrix Power Flo SP1514Z2S4EC, HP 1.5-1.6
The Waterway Supreme was 3420510, HP 2.0 .25 SPL.
Motor pics on post #47 if it helps.

All 2" except about 6" before before after the pump that is 1.5".

Filter pressure about zero. Just changed. New gauge.
 
Texas Splash said:
Filter pressure about zero. Just changed. New gauge.
Click to expand...
That is on low correct? How about on high?

Also, SP1514Z2S4EC is the motor #. Do you know the pump #? Sometimes Hayward puts it on a label tag on the wet end.

I think it may be the SP15932S but I want to make sure.
 
So I created a model for your plumbing based upon what you told me, the pictures of your pad and a few guesses.

docs.google.com

Pool Pump Tools v027 - Texas Splash

ReadMe Version:,v027 Disclaimer,These spreadsheets are provided as is without any guarantees or warranty. Every effort has been made to produce reasonable estimates with these modeling tools. However, unknown measurement errors in the CEC/APSP/EnergyStar data may significantly affect the results...
docs.google.com docs.google.com

The operating point on high speed is as follows:

Flow Rate: 69 GPM
Suction Head: 12'
Return Head: 33'
Pump Suction: 11" Hg
Filter Pressure: 7.5 PSI

The operating point on low speed is as follows:

Flow Rate: 34 GPM
Suction Head: 3'
Return Head: 5.4'
Pump Suction: 3" Hg
Filter Pressure: 0.7 PSI

Suction is maybe a little higher than average but not high enough that it would cause any kind of issues.

But when suction does run higher, it does increase the probability of air leaks,
 
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Back on Friday before the weather rolled in, I did a few tests. My first set was a bust because my equipment pad bladder was leaking on me, so I started over. Then I did a new test with the following results:
1:02 pm - 18psi
1:24 pm - 14psi
1:45 pm - 12psi
2:30 pm - 12psi

At 2:30 is when I decided to try a higher psi of 20 and could never get the blow-thru plug to stay in. But it seemed to hold at 12 psi for a good while. I follow Leaktronics on YouTube who say a good testing psi is 10-15, really no need to go over 15. I wonder if going too high compromised the plug seals.
 
I did try pressure testing with my staff tester that screws into the skimmer. It didn't hold well, much like the 2" extension I made to help hold the plug better. They both lost pressure quicker. Perhaps I was losing pressure at those threads.

A static dye test did not reveal any loss in the summer though.

IMG_20231110_120833362.jpg
 
If it stabilized at 12 PSI, then there is likely no leak in that section of the plumbing. The loss from 18-12 is most likely due to the test setup.
 
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You also have to consider that when you use pressurized air from a compressor, there is a large change in volume and pressure which requires a good deal of thermal equalization to the surrounding pipe. That process can be very slow in plastic piping because it’s a thermal insulator unlike, say, and air conditioner coil which is made out of metal and conducts heat quickly. So I would expect some loss of pressure over time just from the temperature change of the gas used which is air. Air has a lot of water vapor in it and that can store a lot of heat energy.
 
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I would say that all of your testing is most likely pointing to your pipes not being a problem but the pump and head losses in the system. Mark’s analysis and your own demonstration of a completely full pump pot when the run length is short would indicate enough of a vacuum at the suction side of the pump to pull in air from weak seals like the lid or at the PVC unions. I know when my PB installed my Intelliflo that he specifically told the plumber to hard-pipe all the connections at the pump because he didn’t want any unions that would potentially leak and cause problems. I bet my lid still leaks a bit because that seems to be par for the course with pool pump designs, but the pipe connections are rock solid.
 
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DavidLast said:
If I kept running the pump would it get less and less water in it or would it stay the same?
Click to expand...
Do you mean on high? On high eventually the pot gets 100% purged, although I can see VERY tiny air bubbles that appear to be entering from the inlet. On low speed the water level in the pot drops by about 1-2 inches then remains there. That is what it has been doing with both pumps.
 
Texas Splash said:
Do you mean on high? On high eventually the pot gets 100% purged, although I can see VERY tiny air bubbles that appear to be entering from the inlet. On low speed the water level in the pot drops by about 1-2 inches then remains there. That is what it has been doing with both pumps.
Click to expand...
If at low speed, the water level drops and does not drop further, then this is not an air leak as such.

I don't have enough hydraulics to fully explain it; perhaps someone else does. I see this on occasion it is not overly common. From what I observe and guess, the pump is pulling the water out of the pot faster than the vacuum is overcome on the suction pipe. This leads to the balance between the pipe 'suction' and the pump 'suction' changing and the level in the basket is observed to drop.

The brick trick normally fixes it. I suspect the brick wasn't big enough.

I don't think there is a leak to find. I think this is just how this pump will function.
 
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Then where would the air be coming from? It just doesn't magically appear.

It is either an air leak somewhere or outgassing from the water. However, is seems too fast to be the latter.
 
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mas985 said:
Then where would the air be coming from? It just doesn't magically appear.

It is either an air leak somewhere or outgassing from the water. However, is seems too fast to be the latter.
Click to expand...
I think it is air trapped in the pipe system.

What seems to happen is the pump doesnt pull a full basket. I am making an assumption the centrifugal action creates a vacuum of say -100 (whatever units you like, just for explanation) when immersed in 3 inches of water. The pipe restrictions and losses head are perhaps -20 (again whatever units). The difference shows up as 'air' which I am assuming is (compressed) in the pipe normally. When the pump runs at full speed the pressures change perhaps the vacuum from the pump becomes -150 and this is more than enough to pull X volume to, compress the air and fill the pump as this vacuum is enough to pull a full pipe.

My description may be way off. However I see this on enough sites to think it is not too dissimilar to something like this. As I said someone more familiar with hydraulics may be able to explain it better than I can.

The test is if the water level doesnt change in the basket and the pump runs low speed for 24 hours constantly then it is unlikely pulling air. Turning the pump off may result in an unexpected outcome as there could be small amounts of air come back into the pump from the discharge side and that may cause unexpected outcomes.

Hope that clarifies what I mean. Oh and by the way different pumps even with the same published pump curve may act differently as the domestic pump curves do not include the vacuum side, and vacuum can change from one pump to another depending on internal set ups.
 

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