Gurgling/Slurping Noise at the filter

amgclk65

Active member
Mar 26, 2017
28
NA
hello,
I Recently installed a Pentair IntelliFlo xf pump. Over kill of a pump for my setup, Got a great deal on it. I noticed the Pool filter making a slurping sound at higher rpm. Roughly 1500 rpm and over. I did notice some bubbles from the returns. I did check all the basic areas of common leaks. Drain plugs, Basket lid, Also sprayed soapy water over the suction side pipes. I can't find any leaks. Could it be my small pool filter? Prior the Pentair pump I had a Hayward ecostar Vsp. It did not cause the pool filter to make slurping/gurgling noise. So I took a few videos to Let the experts take a listen and see the bubbles at the pump basket. Hopefully I dont have to redo the plumbing.
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wireform

Silver Supporter
In The Industry
Aug 15, 2017
1,215
Spring Valley, NY
Without seeing the plumbing setup it's hard to say but if the pump If overpowered for the filter and piping and can't get the flow the pump needs it'll grab air from the suction side and cause what you're explaining.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
16,950
Bedford, TX
A,

The IntelliFlo XF is used when you need to move a lot of water.. I believe it has 2.5 or 3" plumbing... For that pump you have a pretty small filter.

What happens when you run that pump as slow as it goes?

Why do you need to run the pump faster than 1500 RPM? What does not work at a lower RPM?

Let's see if we can get one of our pump experts to chime in...

Calling @mas985
Calling @JamesW

Thanks,

Jim R.
 

amgclk65

Active member
Mar 26, 2017
28
NA
Hey,
@wireform
I’ll get a picture of my subpar plumbing .
@Jimrahbe
All works to be honest. Triggers the swg at 500-600 rpms. Which is real nice for electricity concerns.
I first noticed it on priming speeds. So i dialed back the priming speed to 1800 rpm. Also have it set to 1800 rpms for a small water fall feature. No suction cleaner. Got a dolphin discovery for cleaning. It does have a infloor cleaning system. Not in use. I capped off the main return for that system. I did noticed water still gets to some of the pop up heads. Which I don’t think has any influence on the noise.
Plumbing is 2in.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,228
Pleasanton, CA
The XF is not much bigger than the EcoStar VS. On typical pool plumbing, they will produce close to the same flow rate (101 GPM vs 98 GPM). The difference in performance is more noticeable for very low head loss plumbing as the XF has a flatter head curve.

If you have bubbles coming out of the returns, you have a suction side air leak. Since you just added the pump, I would look at the fittings/unions that were involved.
 
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Reactions: Jimrahbe
Apr 1, 2020
6
Pikeville, TN
It is quite possible that the bubbles and biggest clue it the noise, your pump is cavitating, because of a restriction to the suction on the pump inlet. you can look up cavitation, but it's a phase change liquid to gas or the water. It is very hard on the impeller and internal parts. I'm guessing you need to increase to size of the inlet pipe or eliminate any restrictions in the inlet line. (I'm assuming the water level is high enough that your not sucking air at the strainer basket. i.e., inconsistent flow of water causing a vortex in the inlet stream, restriction by the strainer and or derbies. (if so raise water level in pool, raise the level of the pump closer to the level of the surface water, might have to use a different design of strainer basket, depending upon the pump design running the pump at a lower speed, but without a veritable frequency drive or a duel speed pump motor, I believe that might mess with the pumps design curve, efficiency, performance and cost of operation, might even make the cavitation worse. It's probably a dynamic head issue and solved by using the correct size pump for the equipment size and design, see if there are any flow restrictions from skimmer to the pump basket inlet, and try removing the surface skimmer to see if it stops. It is also possible that it is simply air trapped in the filter housing and you only need to shut off the pump, loosen the pump filter basket and let the air purge out with the leaking water, then tighten it up again. you could do it with the pump running it's on the suction side. If when you loosen the cover, it starts sucking sucking in air, rather than leaking water out, then you definitely have an inlet restriction.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,228
Pleasanton, CA
You will never "see" cavitation in a pool pump basket. Cavitation occurs in the impeller and the bubbles collapse within the impeller as the pressure rises toward the outer rim of the impeller.
 
Apr 1, 2020
6
Pikeville, TN
when you loosen the lid, water should leak out due to the pressure of the water flowing into the skimmer, If it has suction rather than water leaking than its trying to pull in water. I'm trying to explain the formation of bubbles in the basket without having to explain thermodynamics. it's the same thing that happens when you pull the plunger on a shot needle srynge your trying to fill out of a vile, as you create negative pressure in the area above the rubber plunger, the liquid will turn to vapor, and then back into liquid as its able to equalize in the tube. the needle opening is to small to allow the liquid to flow into the srynge (forgive me, I have a Masters degree but I can't spell for squat) a phase change occurs, due to the low pressure in the srynge, due to the restriction. It is a violent event with a huge amount of energy exchange occurring, but you only see bubbles foam or vapor. technically the cavitation I mentioned occurs in the volute of the pump on the face of the impeller, but if there is a phase change in the pump basket, there is no doubt it is occurring in the volute
 
Apr 1, 2020
6
Pikeville, TN
I'm an Industrial ammonia refrigeration engineer, Chief boiler engineer, 40+ year Industrial Mechanic in the food manufacturing industry, and now retired. I try to explain things so they can be understandable but that results in some technical things being not exactly correct. since the goal here is to find the solution to your question and not for you to pass a engineering examination, I took some liberties, my goal was help rather than to impress you with my knowledge. I feel very lucky I still remember my name, and if I don't touch the wrong thing and get the virus, but you understand that we old folks tend to remember things from the past more that current things. the phase change I was explaining is what makes refrigeration work. low pressure created down stream in the system, and a restriction in the high pressure supply line (expansion valve) the energy created via the phase change, results in several other energy exchanges , expansion, expulsion, expansion, absorption, . . . ok you get it, anyway that's why Mas said what he said about cavitation in the basket. he might have been better able to find another way to explain the same phenomenon I was trying to tell you. sorry for the perversion of technical terms. Please forgive me.
 
Apr 1, 2020
6
Pikeville, TN
It probably will be a loose connection miss-seated gasket, or o-ring. I'm used to being called in after all the obvious things have been eliminated and everyone is scratching their heads looking for other possible causes and solutions. I agree always make sure it's plugged in first before you call out the Calvary. I'm brand new, so don't know the ropes here. Just wanted to help. Hope it's an easy fix.
 

JamesW

TFP Expert
Mar 2, 2011
18,458
when you loosen the lid, water should leak out due to the pressure of the water flowing into the skimmer, If it has suction rather than water leaking than its trying to pull in water
If the pump is Off or On and the pump is above water, water will not flood out of the pump strainer housing when you open the lid.

If the pump is off and below the surface of the pool, water can flood out when the lid is opened.

If the pump is on and below the surface of the pool, water will flood into the pump strainer but it will not overflow when the lid is removed because the water will be being pump out of the discharge.

In any case, it's very unlikely that you would see cavitation in the strainer basket unless the pump was going full speed and the suction was completely blocked.

Even in the worst case, the cavitation bubbles would probably all be at the intake of the impeller with none visible in the strainer lid.
 
Last edited:

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,228
Pleasanton, CA
technically the cavitation I mentioned occurs in the volute of the pump on the face of the impeller, but if there is a phase change in the pump basket, there is no doubt it is occurring in the volute
The volute is on the pressure/discharge/impeller outlet side of the pump and it is impossible to have cavitation on the pressure side of the pump. The impeller sits between the pump basket and the volute and cavitation will only occur in the inlet of the impeller where the pressure has the potential to be below the vapor pressure of water (0.5 PSIa, -14.2 PSIr @ 80F). Once generated, the bubbles will then collapse very quickly as they travel up through the impeller from low pressure to high pressure. So there will be no cavitation bubbles in either the pump basket nor the volute because the pressure in both locations will exceed that which is required to generate and maintain vapor bubbles.
 
Last edited:

amgclk65

Active member
Mar 26, 2017
28
NA
hello,
I finally got the noise to go away. It was a leak on the suction side. Main drain to be exact. I'm running suction from the skimmer only and no noise or bubbles on the return. Ill have to redo the pluming from the main drain again. The pipes are off set (main , skimmer) coming from the ground . So I can't do the proper 3-way valve then onto the pump. Maybe ill just keep the main drain capped. thanks for the all the info fellas ..
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,228
Pleasanton, CA
The only issue might be that you could be losing water through the MD lines somewhere. Have you done a bucket test to see if you are losing water?
 

amgclk65

Active member
Mar 26, 2017
28
NA
I haven't . I turned off the water fill valve some time last year. The water level has not dropped. If that means anything.