Bubbles coming through return lines - can't determine where a leak might be

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anthonypool89

anthonypool89

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Aug 26, 2016
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Berks County, PA
This is not a new problem but has been getting worse, especially after recharging the DE filter, at which point there is maximum pressure coming through the lines. There is a visible air/ bubble stream shooting into the pool from both return lines. So what results is a good deal of foam in the pool - even once the return line pressure starts to decrease. When swimming towards the shallow from the deep end, I can always see what looks like loads of bubbles sort of jumping up from the water line. My daughter remarked about this years ago already.

So this season I thought I'd try to troubleshoot a bit - replaced the pump strainer gasket and tightened as many PVC couplings, etc. as I was able to. I've not yet replaced the filter tank o-ring. I must say that there is often air that seems to accumulate at the top of the filter tank that I then release with the valve. When I do that, sometimes the return line bubbles do subside - for awhile.

Thing is - how to be sure if it's pressure or suction side? There is always what looks like lots of air / bubbles swirling around in the pump strainer, so would that indicate suction side? If the problem is underground plumbing between skimmer / drain / pump, that's probably a worse-case issue. Pressure side is probably easier to both diagnose and fix? Any advice appreciated. It's not a real big deal, unless it's contributing to my constant filter pressure increase (?) 🤔 I've experimented with turning the diverter valve more towards skim or drain to see if there is a noticeble increase or decrease in the amount of air coming into the pool, but it doesn't seem to make all that much difference. Just hope it's not an underground plumbing issue. I don't have an issue with loss of water.
 
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Air would come in on the suction side. On the pressure side, you would see water squirting out where there are any leaks. Other than the pump lid gasket, one of the likely places for the air leak is the diverter valve itself. Have you tried taking a hose and squirt water on the pump lid, PVC connections, and diverter valve to see if the bubbles disappear?

 
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How can you assess whether the diverter valve might be leaking since it's always under water in the skimmer at the bottom of the pot? Good point about squirting water on the various places. I did that but only to see if any bubbles formed at those places - didn't check to see if it resulted in less air entering the pool.
 
anthonypool89 said:
How can you assess whether the diverter valve might be leaking since it's always under water in the skimmer at the bottom of the pot?
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Many of us have a 3way valve or 2 before the pump at the equipment pad. You have the valve inside the skimmer instead. Yours isn't the source but it might be for anyone else. (y)

Here is mine, 2 skimmer lines and a main drain line. 20220523_160823.jpg
 
I can supply a picture. My set-up at the filter is pretty simple - the tank has a handle that's either in the up or down position. Up for backwash / discharge and down for normal circulation. That's it. No other option - can't vacuum to waste, etc.
 
K...here is the equipment. I ran alot of water from the hose at quite a few different places to see if the amount of bubbles coming through the returns decreases, and it seems that the leak is at the bleeder valve. I've suspected this for some time. Depending on how I turn it, more or fewer bubbles appear right there at the top of the tank. I have a new valve but just never got around to putting it on yet. Will do that and hopefully solve most of the problem. I'll also replace the tank o-ring. Even if that's not part of the problem, it's time to do it anyway.IMG_2022.jpegIMG_2023.jpegIMG_2024.jpeg
 
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+1. Literally why you see bubbles, because air is being forced out and not sucked in.

The leak causing the air in the tank, and the bubbles in the return is before the pump.
 
Newdude said:
The leak causing the air in the tank, and the bubbles in the return is before the pump.
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Not sure what you mean by "air is being forced out" ? So anyway where's the air coming from? If before the pump, that would appear to suggest either an underground problem or else the 2 fittings before the pump. All that long piping that goes to the heater is after the pump. All I know is that when I adjusted the bleeder valve it appeared to decrease the amount of aeration in the shallow end. If the air is being drawn in underground between skimmer and pump, nothing to be done (well, yeah, short of digging up the lines - forget that. Got enough problems here.)
 

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anthonypool89 said:
Not sure what you mean by "air is being forced out"
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Think of blowing bubbles with a straw. The bubbles are the end result. You are the source.

Your small air leak is collecting in the filter and when you let it out, the returns clear. It starts collecting immediately in the filter and at some point will show at the returns again.
 
Wow....I've been told I'm a big windbag already.....😁 So...we're back to trying to track this down. I've not yet tested putting water against the big threaded pipe union that's closest to the stones.

How to Get Rid of Air Bubbles in Your Pool - Pool Pump Service #2 in this source indicates bubbles could be caused by the bleeder valve. I will try using the hose and putting water against a few more unions near the pump, but short of that have no idea what else to do.
 
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anthonypool89 said:
Wow....I've been told I'm a big windbag already.....😁 So...we're back to trying to track this down. I've not yet tested putting water against the big threaded pipe union that's closest to the stones.

How to Get Rid of Air Bubbles in Your Pool - Pool Pump Service #2 in this source indicates bubbles could be caused by the bleeder valve. I will try using the hose and putting water against a few more unions near the pump, but short of that have no idea what else to do.
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The only way a bleeder valve can cause an air leak is when you shut the pump off, you can have air coming in through the bleeder (or lots of other places on the pressure side) and it will cause you to lose prime as all the water is able to flow back to the pool on the suction side because nothing is holding it up. But after you bleed that air off after pulling prime it won't cause further bubbles.

They only above ground sources I can see on yours are the union, any other couplings before the pump, the pump basket lid, and the pump drain plug.
 
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Well, worth a try replacing the pump drain plug or at least take it off and see what condition the gasket is in. Pump basket lid had a new gasket on it. There another plug towards the back of the pump. Probably take that one off and check it also. It'd be nice to actually have the time to do some of this other stuff instead of always draining the tank, taking the filter apart, cleaning everything, and recharging the DE. So far been doing that every 2-3 days the past nearly three weeks.

I sent an email to a reliable pool technician to see if he can help me out. I simply don't have much time to devote to this issue but would like it resolved. Let me ask this...is there ANY chance that the suction side leak, i.e. air being drawn in somewhere, could ALSO play a part in the constant filter pressure increase I'm seeing? Any possible link there?
 
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Rancho (love the name by the way!) thanks....all I did is tighten the grey one - did not actually have it apart. I didn't do anything with the white one yet. I was hesitant to get into actually having to take any plumbing apart, although it looks like if I loosen the grey and white unions, that entire elbow section will easily remove (?) Only way to really check the o-rings in there.
 
You can TRY to wrap each joint tightly with Saran Wrap to see if it reduces the amount of bubbles. I've heard about it but never tried it. Maybe it'll work?

I'm guessing you tried the water hose trick. My thought was the running water might not reach the bottom of the white union while checking for leaks.
 
Rancho Cost-a-Lotta said:
My thought was the running water might not reach the bottom of the white union while checking for leaks.
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Not sure I sprayed any water on the white one. Best is to take them both apart. Filter pressure has started going up (again) so as soon as that happens the air coming in through the returns is much less noticeable. Tops on my list is solving the constant pressure increase situation, then next would be the air leak.

Was curious as to where you are - my daughter will be moving to Irving this summer - not far away from your area. She is told Irving is a nice area - never been in that part of the state.
 
Irvine is about 30 minutes away from me in Orange County ( about 6 hours in traffic:)). It has a reputation as a very safe city, known for its affluence. I don't think you can find a safer city for her to live in California.
 
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