losing prime overnight

[cholmes28]

I have an inground pool which is losing prime overnight. If I turn off pump, I see a single air bubble form every 5 seconds or so in the filter basket housing of the pump. I went through the following steps to try and isolate the issue..

1. Skimmer/Drain closed, multiport on "closed" - no air leak
2. Skimmer/Drain closed, multiport on "filter" - air leak
3. Skimmer open, Drain closed, multiport on "closed" - air leak (I can hear air moving in the multiport)
4. Skimmer closed. Drain open, multiport on "closed" - air leak (I can hear air moving in the multipart)
5. Skimmer open. Drain open, multiport on "closed" - air leak (I can hear air moving in the multipart)

I already sprayed soapy water on everything, and was not able to see any bubbles get sucked into anything.

The above steps lead me to believe there is an issue with the multiport, like perhaps the spider gasket. The one thing that has me confused is why on #2, do I not hear any air moving in the multiport even though I still have the air leak? Only thing I can think of is that when the skimmer or drain is open in #3 or #4, there is more of a vacuum which sucks more air, and thus I can hear it. Thoughts on my theory? Should I try replacing the spider gasket?

 

[Richard320]

It sounds to me like your leak is at the waste port of the multiport. Is it exposed or hard-plumbed?

 

[cholmes28]

I am assuming the waste port is the line that the backwash hose is connected to? If so, then it is exposed. It is PVC and makes a few elbows around the equipment area, then I have a vinyl hose attached to it with a hose clamp. Is there a way to ensure that the waste port of the multi port is bad? Will a spider gasket fix this, or is there another fix, other than replacing the multiport?

 

[Richard320]

If it is leaking inside the multiport, the spider gasket fixes it. That's what I'd attack first, since a stiff or unseated gasket may seal under pressure but leak under suction or vice-versa.

Put a blob of shaving cream in the end of the backwash pipe and then see if it gets sucked in when things are off. Or hold some incense or a cigar or a cigarette near it and see if it draws smoke in. Then you'll know if that's the culprit.

 

[cholmes28]

I removed the top of the multiport, and as far as I can see the spider gasket looks to be in great shape. No cracking or stretched spots, and it is seated very firmly. In fact, it would have taken a screwdriver to pry it out. The o-ring around the top looks brand new. Before I spend $25 on a new gasket, I had a question. If you are correct that I am leaking air in the waste port of the multiport, then could there be any other cause except for a bad gasket? I am going to try the shaving cream test shortly.

 

[Richard320]

I removed the top of the multiport, and as far as I can see the spider gasket looks to be in great shape. No cracking or stretched spots, and it is seated very firmly. In fact, it would have taken a screwdriver to pry it out. The o-ring around the top looks brand new. Before I spend $25 on a new gasket, I had a question. If you are correct that I am leaking air in the waste port of the multiport, then could there be any other cause except for a bad gasket? I am going to try the shaving cream test shortly.

cracks, maybe? Warpage? I don't know.

 

[cholmes28]

ok, thanks for your input. I will try shaving cream, if it is sucking air, via the backwash line, then I will replace spider gasket, and if that doesn't fix, then the only other thing I can think of to do is replace the multiport.

 

[cholmes28]

Ok, I tried the shaving cream, and it did not get sucked in when I shut off the pump. I did notice that I could hear air moving inside the multiport when pump was off. When I closed the multiport, drain and skimmer, the air noise stopped. Could there be a leak in the pump housing, or would that be ruled out by one of my tests in the initial post? Other than replacing gasket or entire multiport, I am running out of things to test. You have any further comments?

 

[duraleigh]

Any leak around the multi-port is a pressure side leak and should be characterized by visible water coming from the leak when the pump is running. Is that the case?

 

[mas985]

A multi-port leak may not always leak water when the pump is on. Sometimes these leaks can be unidirectional much like a pump lid. When the pump is off and the multi-port is above the water line, there is a net suction around the valve so it is possible to leak air in. But another place where this can happen is at the unions of the multi-port.

 

[duraleigh]

A multi-port leak may not always leak water when the pump is on

How often do you see that....10% of the time? 50%? I understand how it can occur but I don't understand if the possibility is 50/50 or remote.

 

[mas985]

I seen several cases on this particular issue on both this forum and other forums. Once the gasket/o-ring is fixed, the problem goes away. But in this particular case, the leak is dependent on the multi-port valve position and the pool valve positions so that tells you right away that it has something to do with the multi-port.

1. Skimmer/Drain closed, multiport on "closed" - no air leak
2. Skimmer/Drain closed, multiport on "filter" - air leak
3. Skimmer open, Drain closed, multiport on "closed" - air leak (I can hear air moving in the multiport)
4. Skimmer closed. Drain open, multiport on "closed" - air leak (I can hear air moving in the multipart)
5. Skimmer open. Drain open, multiport on "closed" - air leak (I can hear air moving in the multipart)

Only in number 1 does the air leak stop. This is because the suction is removed at the multi-port when the suction valves are closed and the multi-port valve is closed. Note that as long as there is path to the pool, the valve leaks. This is because the pool at a lower level than the valve creates a small vacuum at the valve.

 

[duraleigh]

cholmes28,

If your pump re-primes in the morning in less than a minute, I would let it go and never worry about it. How long does it take to re-prime?

 

[cholmes28]

cholmes28,

If your pump re-primes in the morning in less than a minute, I would let it go and never worry about it. How long does it take to re-prime?

It usually re-primes in less than 1 minute, but the other day I noticed that the pump had been on for at least 20 minutes, and there was no water in the pump housing. It was hard to prime, and the only way I could get it primed was to shut off drain, and only pull from skimmer, and put a ton of water from the hose into the pump housing. That is the only time it was like that though, but it worries me that if it happens again, I may burn out my pump, and I just replaced the motor, so don't want to have to do that again!

I am going to replace the o-rings in the pump drain plugs, because my neighbor had exact same issue, and that is what fixed it.

 

[cholmes28]

Any leak around the multi-port is a pressure side leak and should be characterized by visible water coming from the leak when the pump is running. Is that the case?

There is no visible water leaking anywhere when pump is running or not running. I even sprayed everything down with soapy water, and cannot see any signs of pressure leak, or bubbles getting sucked in. The only place I notice water collecting is in the center of the multiport where those notches for the various positions are. I have even dried that out, and when I come back several hours later, there is a bit of water in there.

 

[cholmes28]

Problem Resolved!!

I removed the 2 drain plugs on the pump housing, and noticed that there was no o-ring. I bought 2 new plugs with o-rings, screwed them in, and ran through all the scenarios, and there is no air leak as of yet. I had long suspected that since the issue started the day after the pool guy opened the pool in the spring, that it may have been caused by something one does when they shut down a pool. He probably stripped the threads screwing in one of the plugs or something. Many thanks for everyone's input. This site is very helpful, and replies are prompt and educated.