Spa Check Valve Pulsates and Spa Drains Into Pool Overnight

HBStoneGroove

Member
Mar 21, 2025
12
Huntington Beach
I am stumped. My spa drains back into the pool overnight down to the level of the jets. I have replaced the inline check valve (Flo Systems see-through valve) and the guts of both Jandy valves (suction and return). I can see the flapper inside the check valve pulsating and hear it making a glug glug glug noise. If I close the inline "spa bypass" valve the noise and glug glug glug stops, as does the pulsation of the flapper.

I initially suspected it was a defective flapper/check valve for the spa bypass since it was 20 years old. It is not spring loaded and I suspect just uses the pressure from the spa water to push the flapper against its seat. Rubber on the old flapper was shot and I thought for sure I had it fixed by simply replacing the ancient check valve. Nope.

I then ordered two new Jandy three way valves (also twenty years old) and replaced the valve guts (left the glue-together housings intact). Still losing water and still have glug glug glug with flapper pulsations. What am I missing here? Pretty simple system.

I read somewhere here that another guy found his salt cell causing oscillation in his check valve because the salt cell had its own check valve? My cell has been dead for years and I no longer have need for it. Should I just cut it out and run a straight piece of pipe?

IMG_1857.jpg
 
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If you close the blue T handle valve, does that prevent the spa from draining?
If so, then the check valve should be replaced.

A SWCG does not have a check valve or least not any I am familiar with. A SWCG does not need a check valve in front of it.
If your SWCG is old and non-functional, then replace it or remove it. It may have a lot of calcium buildup in it which affects flow performance of the system.
 
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HB,

When you shut off the pump at night, does the water in the pump basket, drain back into the pool overnight?

When you turn the pump on the next day, do you get huge bubble out of the pool returns for a 15 seconds or so?

Do you get any drips of water from around the check valve you just replaced?

Thanks,

Jim R.
 
If you close the blue T handle valve, does that prevent the spa from draining?
If so, then the check valve should be replaced.

A SWCG does not have a check valve or least not any I am familiar with. A SWCG does not need a check valve in front of it.
If your SWCG is old and non-functional, then replace it or remove it. It may have a lot of calcium buildup in it which affects flow performance of the system.

Yes. If I close the blue handle check valve the draining stops and the flapper pulsation stops. That see-through check valve in the image is brand new. I thought for sure the old, worn out one was my problem.

I feel like I'm either 1) losing gravitational water pressure (elevated spa) on the spa side of the new check valve, or 2) I'm experiencing slight pressure on the pool side of it that is forcing the flapper open momentarily and repeatedly. It's not as if the flapper is staying ajar the whole time.

Like everyone else, I could add valving and try other modifications, but my personality is one that keeps saying "it worked properly for twenty years and now it doesn't. Why is that and what can I do to get it to function as it used to"? Probably a character flaw.
 
HB,

When you shut off the pump at night, does the water in the pump basket, drain back into the pool overnight?

When you turn the pump on the next day, do you get huge bubble out of the pool returns for a 15 seconds or so?

Do you get any drips of water from around the check valve you just replaced?

Thanks,

Jim R.

1) No. Water in the pump basket remains.

2) I do not think so but I will check tomorrow morning.

3) Nope. Check valve connections are tight. I cannot see anywhere that would allow air to suck back into the system.
 
Cut at the red lines and replace that section with a Jandy check valve and a Jandy two-way valve.

Put a check valve at the red rectangle.

That may be where I end up. Trying to make it work as it has for twenty years first. I hate not figuring things out.

Question, though. Why the recommendation to place two new-technology (spring loaded) check valves in the spa line? Just for some overkill? I'm not opposed to it but after staring at the equipment for an hour trying to wrap my head around exactly what is even going on (I'm a generally very handy and mechanically inclined pool novice) I came to the conclusion that a check valve in each of the locations you stated were a bit redundant since the three way valve (pool return/spa return) was defaulted to spa-closed.

Further, since I have a non-functional chlorine generator, couldn't I just ditch that bypass altogether and have the pool/spa return valve open to both pool and spa full-time, and then install the check valve where you placed the red rectangle? I thought the entire purpose of the bypass was to allow chlorinated water to be diverted in a lower quantity (hence the smaller diameter pipe) so as to avoid the spa being overchlorinated as compared to the pool.
 
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HB,

I have no experience with that particular check valve, but have a question anyway... :mrgreen:

Is there a specific orientation required when installed?? In other words, does the flapper point up, or down, or sideways, or does it not matter at all??

Edit... if it worked for 20 years, what changed??

Thanks,

Jim R.
 
HB,

I have no experience with that particular check valve, but have a question anyway... :mrgreen:

Is there a specific orientation required when installed?? In other words, does the flapper point up, or down, or sideways, or does it not matter at all??

Edit... if it worked for 20 years, what changed??

Thanks,

Jim R.

There is labeling on the check valve that tells you how to orient it depending on vertical vs horizontal installation. It's correctly installed with the hinge pointing toward the sky.

"What changed" is I heard thumping noises when I was piddling around near the equipment and I am mentally deranged to the point where I needed to find the source. I had noticed water loss in the spa for a little while and didn't pay it much attention until now.

I have a pool guy who keeps the water clear and clean and handles filter maintenance but he doesn't repair anything so all that falls to me, and I have no real pool knowledge to speak of. That's why I really appreciate you guys.
 
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Yes. If I close the blue handle check valve the draining stops and the flapper pulsation stops. That see-through check valve in the image is brand new. I thought for sure the old, worn out one was my problem.

I feel like I'm either 1) losing gravitational water pressure (elevated spa) on the spa side of the new check valve, or 2) I'm experiencing slight pressure on the pool side of it that is forcing the flapper open momentarily and repeatedly. It's not as if the flapper is staying ajar the whole time.

Like everyone else, I could add valving and try other modifications, but my personality is one that keeps saying "it worked properly for twenty years and now it doesn't. Why is that and what can I do to get it to function as it used to"? Probably a character flaw.
All of these comments points to the check valve. There is something about the new parts that were installed or maybe the housing (internal) is worn that is not allowing a proper seal.

If you want to minimize your PVC work, then just cut out the old check valve housing and put in a new Jandy check valve (leave the Blue T handle in place). But I agree with James, that the Blue T handle valve will eventually go bad and you would have to cut it out as well - so while you are making the 2 cuts - remove both the old check valve housing and the Blue T handle valve and put in new Jandy check valve and 2 way valve. Both allow replacement of internals without removing the housings from the PVC plumbing.
 

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All of these comments points to the check valve. There is something about the new parts that were installed or maybe the housing (internal) is worn that is not allowing a proper seal.

If you want to minimize your PVC work, then just cut out the old check valve housing and put in a new Jandy check valve (leave the Blue T handle in place). But I agree with James, that the Blue T handle valve will eventually go bad and you would have to cut it out as well - so while you are making the 2 cuts - remove both the old check valve housing and the Blue T handle valve and put in new Jandy check valve and 2 way valve. Both allow replacement of internals without removing the housings from the PVC plumbing.

I am leaning toward what James has suggested if for no other reason than to get that blue-handled valve out of there. It has become increasingly hard to operate and I fear the next turn might be its last, causing me an emergency situation. And a Jandy check valve is also certainly an upgrade.

However, look at my edited response to him above. Do I even need that bypass contraption at all? Can't I just abandon it altogether by leaving the pool/spa return valve open to both ports and install a check valve where he has indicated with the red rectangle? What is the spa bypass giving me at this point since I have no functioning chlorine generator?

I'm not opposed to PVC work. My layout seems to lend itself to some easy measurement and cuts since everything is 90 degrees. I could rebuild everything above the red lines in the image below.

IMG_18572.JPG
 
HB,

That is crazy!!!!! Why would that be??? :scratch:

I'd fill my pool in if it could not be a saltwater pool... :mrgreen:

Thanks,

Jim R.

Just laziness and a lack of knowledge/understanding. I let my pool guy talk me into abandoning it all when the cell and control unit took a dump and it was going to be mega bucks to replace them. He said "that technology hasn't turned out to be as good as it was sold to be and lots of folks are just going back to standard chlorine." I said have at it and haven't looked back. Should I?
 
HB,

How do you currently add chlorine to your Pool?

Do you buy it or your "pool guy"?

"Most" people that convert to a saltwater pool would never go back to a standard chlorine pool.. There are a few, but not many. :mrgreen:

If you let your pool guy take care of the pool, you might not notice the difference.. But, If you take care of the pool yourself, then you'd notice how easy the maintenance is on a saltwater.
pool.

That said... Whatever works best for you, works for me.. :goodjob:

Thanks,

Jim R.
 
I am leaning toward what James has suggested if for no other reason than to get that blue-handled valve out of there. It has become increasingly hard to operate and I fear the next turn might be its last, causing me an emergency situation. And a Jandy check valve is also certainly an upgrade.

However, look at my edited response to him above. Do I even need that bypass contraption at all? Can't I just abandon it altogether by leaving the pool/spa return valve open to both ports and install a check valve where he has indicated with the red rectangle? What is the spa bypass giving me at this point since I have no functioning chlorine generator?

I'm not opposed to PVC work. My layout seems to lend itself to some easy measurement and cuts since everything is 90 degrees. I could rebuild everything above the red lines in the image below.

View attachment 633732
The Pool and Spa valve directly after SWCG is to switch between the Pool and Spa modes. Pool mode is pool suction and pool return only. Spa mode is spa suction and spa return only. There is no overflow from sap to pool in either of these modes.
Then there is the Spa Spillover mode - suction from the pool and return to the spa or to spa and pool. I think this is what you are referring to by just having the one valve that is open to both spa and pool returns.
The only issue with this is that we recommend not spilling over from your spa to the pool the full time that your pump is running. Continuous aeration will raise your pH and you will be adding more MA.
That is why the by pass is put in.

The system is put in pool mode. Then either once or twice a day, open the by pass valve to allow water to go to the spa to refresh is with chlorinated water. This also allows spillover to the pool.

If you install your SWCG again - it will have a setting for output in pool mode and another in spa mode. Depending on how often you use SPA mode, you may not need to reun the spillover mode as often.

Hope this makes sense.
 
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Crazy update. So I decided to see what effect operating the various valves might have on the situation and something extremely strange happened. When I move the pool/spa return valve from the position shown in the image I posted (open to pool and closed off to spa) to the opposite configuration, I noticed the flapper pulsation stopped when I had the valve slightly open to the spa. I then sloooowwwly closed off the spa position and the flapper remained still and pool water did NOT drain back overnight.

So it appears the system is capable of functioning correctly with the equipment I currently have in place. However, after the system ran its normal schedule the next day, the flapper returned to its habit of pulsating and water draining back to the pool. It's almost like there's an air bubble in there somewhere that is keeping the spa side pressure against the check valve from being what is needed to keep the flapper slammed shut.
 
HB,

Have you rebuilt the Return valve, by replacing the diverter and O-Rings??

Thanks,

Jim R.
All valves are new with the exception of the blue handled valve for the spa bypass.

Tried again today and by just cracking the spa return open just a tad and then slowly returning the valve to spa-closed, pulsation stops. Craziest thing.

I've ordered all of the parts James recommended and I'm going to rebuild the outlet side of the pump plumbing. Enough already.
 
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Cut at the red lines and replace that section with a Jandy check valve and a Jandy two-way valve.

Put a check valve at the red rectangle.

View attachment 633600

1745187772669.png


So I have assembled all the parts necessary to complete this task but I have a question before I cut off the pipe (spa return) where the red rectangle is.

I have an elevated spa. When I cut this pipe in order to install the check valve, will water pour out of it until the level in the spa and the level in the pipe are equal? Should I try and drain the spa down as much as possible before I cut? I obviously need to glue the check valve in and I can't do that if that pipe is full of water.
 

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