Suction side leak help

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BlueWater6334

Bronze Supporter
May 31, 2023
18
Southeast Louisiana
Hello,

I'm trying to track down a possible suction side leak. Any advice?

Attached picture shows the pump inlet pipe which comes from 3 valves (shallow skimmer, main drain, and deep skimmer).

Symptoms:
  • When the pump is shut off, the water level in the pump basket starts going down slowly, probably takes about 30 minutes to empty.
  • The pump has to re-prime every time it starts back up (takes ~10 seconds).
  • There appears to be large bubbles that come from the pump inlet pipe as the water level slowly decreases when the pump is off. These bubbles are infrequent, like every 1-3 minutes a big bubble comes through the inlet pipe into the pump basket.
  • If I hold my hand on the inlet pipes, I can feel the vibration of the bubbles/gurgling when the pump is off.
  • The bubbles from the inlet pipe still appear and the water level in the pump basket housing still lowers even if I close all 3 valves. So this tells me either the valves don't work or the water is being sucked towards the filter/pool returns?
  • I can hear gurgling sounds some times from the sand filter when the pump is off.
  • The water level in the pump basket housing does go below the inlet pipe and I can still hear gurgling despite the water level being below the inlet pipe.
  • The sand filter pressure gauge goes immediately to 0 when the pump turns off and sounds like water drains from the filter area.
  • Over the past couple days I have been having to add water to the pool because the water levels gets to the bottom of the skimmer.
  • When the pump is running, there are bubbles swishing around the top of the pump basket housing. The bubbles never completely go away (this has always been the case since we bought the house ~7 years ago really).
  • The pump and water circulation seem fine. I could run it 24/7 without issues.
  • There used to be bubbles coming from the pool returns, but I lubricated and tightened the pump basket lid o-ring and I no longer notice bubbles from the returns.
  • There are no visible water leaks from any of the above ground plumbing.
  • I don't notice any water drips from the pump area when the pump shuts off.
  • There are no wet spots anywhere and no wet/damp ground.

Thanks for any help.
 

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Welcome to TFP.

You have a leak in your pool system with it not holding pressure but the leak does not need to be on the suction side. The leak can be anywhere in your pool plumbing letting air in when the pump is off.

What is the elevation of your pool equipment relative to your water level?

What is the water level in your skimmers?

Post pics of your pool and all of your pool equipment.
 
Thanks for the reply.

> but the leak does not need to be on the suction side.
Click to expand...

Good to know, I was thinking it was suction side because of the bubbles in the pump basket housing when running.

> What is the elevation of your pool equipment relative to your water level?
Click to expand...

Pool pump is about ~20 inches higher than the water level of the pool.

> What is the water level in your skimmers?
Click to expand...

I try to maintain the water level at about half way up the skimmer opening. Just this morning I went out there and the water level was at the bottom of the skimmer opening so I had to refill again after refilling it to half way yesterday evening.

> Post pics of your pool and all of your pool equipment.
Click to expand...

Attached pictures showing everything. Do know that the pool heater has been removed from the plumbing circuit, I plan to have the gas disconnected and removed totally soon. Image pump_1.jpg shows the shallow side skimmer relative to the pool pump.
 

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> I would slowly and systematically check every valve, union, connection etc for a potential air leak.
Click to expand...
Any tips for this? I tried listening closely everywhere I could last night when it was quieter and didn't hear any hissing sounds. I may be trying to listen for the wrong thing though.

With the bubbles in the pump basket housing, it makes me want to think that there is a leak somewhere around the inlet pipes, but where would the water be going? Nothing is wet.
 
An easy first step would be to rebuild the three suction side valves. Lubricate with Magic Lube II or another silicone lubricant (NOT SEALANT and not PTFE/Teflon lube).

Amazon.com: ATIE Neverlube Valve Cover & Shaft O-Rings Replacement Fits for Jandy/Pentair Compool 2-Way/3-Way Valves (Parts Numbers: R0487100, 1132, 192039Z, 51016200Z, O-158, O-515-KIT-9) (5 Pack) : Patio, Lawn & Garden

Amazon.com: ATIE Neverlube Valve Cover & Shaft O-Rings Replacement Fits for Jandy/Pentair Compool 2-Way/3-Way Valves (Parts Numbers: R0487100, 1132, 192039Z, 51016200Z, O-158, O-515-KIT-9) (5 Pack) : Patio, Lawn & Garden
www.amazon.com


 
That seems reasonable. I ordered the new valve o-rings and will report back. I've been using this "DANCO Waterproof Grease" for lubricating my pump basket o-ring, is it ok to use?
www.homedepot.com

DANCO 1/2 oz. Waterproof Grease 80360 - The Home Depot

The Danco Waterproof Sealant Grease is ideal for lubricating faucet stems, valves and cartridges when repairing a leaky faucet. Waterproof faucet grease helps reduce friction provides long-lasting lubrication
www.homedepot.com
 
You have some pipes capped. Are the caps glued on? Any opening around a cap will allow air in to depressurize the system when turned off.
 

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> You have some pipes capped. Are the caps glued on?
Click to expand...
There is a short pipe coming from the sand filter MPV with a cap on that is not glued. When I need to backwash or otherwise drain water from the pool I attach a vinyl drain hose to it with a clamp (after removing the cap) so I can direct the water. I'm under the assumption that when the MPV is on Filter setting, then that backwash pipe should be closed off, but I suppose that could be a source of air leakage?

It used to be connected to the pipe directly below it (that also has a cap, but this pipe isn't connected to the pool system any longer). That pipe goes underground to a drain that just bubbled the waste water up near the pool equipment so it just flooded the entire area. No idea why they did that when it was installed. So when I bought the house I cut a section out (between those 2 caps you see) so I could attach a hose to direct the waste water further away.
 
ajw22, your comments about the caps led me to investigate the MPV more closely. I sprayed some soapy water around the MPV and noticed bubbles getting sucked into the MPV when I turn the pump on and the bubbles get pushed back out when I turn the pump off. Can see it in this video. filter_mpv.mp4

I suppose there's some seal/o-ring in the MPV I'll need to replace.

Pentair Tagelus High Rate Sand Filter
Model TA-60D
P/N 145241
 
Last edited:
Put a shutoff valve on that pipe rather then messing with the MPV spider gasket.
 
BlueWater6334 said:
Good idea, I'll look into a shutoff valve.

I think I still need to replace an o-ring or something in the MPV though? The leak seems to be where the "lid" of the MPV connects with bolts and nuts, in that seam.
Click to expand...
Ah, there are O rings that seal the stem. That is an easier fix then the spider gasket.

Find a parts diagram for your MPV and you will see the parts.
 
So I tried re-seating the existing o-ring with some new lubricant to see if it'd help (it didn't), but I did discover the spider gasket was glued to the "lid" part of the MPV. All the videos about MPV repair I've found show the spider gasket attached to the MPV inside. Is this right?
 

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