Help!! Spa losing water overnight...trying to find culprit?

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CajunGuy

CajunGuy

Well-known member
Apr 6, 2016
346
Louisiana
My spa is losing about 4-5" of water overnight. Attached is a picture of my pool pad equipment. I have the one main return line that splits off (pentair diverter valve circled in yellow) into "spa" on the left and to "pool" on the right. I thought it was the check valve on my spa return line (green circle) so I replaced that with a brand new OEM valve, but the spa still would lose water overnight. Then I noticed the diverter valve (yellow circle) was also leaking water out the top. So I took apart the diverter valve to inspect and noticed the grey door seal was torn/damaged and the o-rings had some wear to them. I have replacement parts coming in for the valve door and gaskets, but I have a couple questions:

1. How could the spa still lose water if the check valve is new and working properly? Shouldn't that seal and prevent any backflow when pump turns off?

2. Is it common for the grey diverter valve door seals to tear from use over time and do you guys think this could be the culprit of my spa losing water over night? Not sure what else could be causing it.

3. Do I need to lube the grey door gasket on the new replacement door?Compress_20240318_165232_2113.jpg
 
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Guy,

Show us pics so that we can see all the inputs to your main pool pump.

Once we see the whole set up, we can give you some tests to perform.

Is this a new issue, or has it never worked??

Thanks,

Jim R.
 
Jimrahbe said:
Guy,

Show us pics so that we can see all the inputs to your main pool pump.

Once we see the whole set up, we can give you some tests to perform.

Is this a new issue, or has it never worked??

Thanks,

Jim R.
Click to expand...
Jim, thanks! See attached photo for entire setup. Initially, the first 6-7 years the spa never lost water. Probably the last year or 2 I noticed it started to lose water overnight. Then became a little more increasing the last 6 months. I've replaced the check valve (pink circle) thinking that was the culprit...but it still lost water overnight after replacing. Then I noticed the main return diverter valve leaking water out the top, so I took apart the diverter valve yesterday and noticed the grey door seal was torn/damaged and the o-rings on the shaft were worn. I ordered the oem replacement parts and will install those this week.

On a side note, I noticed I have a small leak at the top of my sand filter when the pump is on, so I have a replacement gasket for that too which I will swap out next week also.

Also, please look at my 3 questions in the original post and tell me what you think?Compress_20250216_183712_2009.jpg
 
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Guy,

1. About 90% of the time, the check valve in the spa return line is bad... But a leaking Intake valve can also cause the drain down..

2. The grey seal on the diverters should not be torn and of course this can cause a leak.. But... Since your Return valve (the one after the SWCG) is offset to allow for your spa spillover.. It is not sealing anyway, so a leak there should not cause the spa to drain down, unless the check valve is also bad..

3. I would add a little pool lube to the diverter seals. It can't hurt.

I suggest that your replace the diverter in your Return valve.. Then close the Return valve so that no water flows to your spa return pipe.. With the spa full, shut the system down and see of the spa still drains down..

If the spa does not drain down with the spa return pipe shut off, then open the Return valve and see if the spa drains down.. If it does, the check valve has to be bad.
If the spa drains down with the spa return pipe shut off, then the problem is most likely at the Intake valve.

Thanks,

Jim R.
 
Jim, when you say "intake valve"...are you referring to one of the 3 blue suction lines?

I do remember when we first bought the house, I could leave the main return diverter valve partially open (with water returning to both spa and pool) and with it open overnight, the spa would NOT drain down or lose water. I'll replace the main diverter valve internals and then run your test and report back.

Maybe the new check valve I installed a while back (pink circle) was defective or I possibly could have installed it wrong I guess.
 
Guy,

The Intake valve is the one directly in front of your main pool pump.. It selects if Spa water or Pool water gets sucked into the main pump..

The Return valve is the one right after the SWCG and it sends water to either the Spa or the Pool.. Or, in your case, because it is offset, it sends a little water to the Spa and most of the water back to the pool.

If you use the Return valve to shut off the spa return pipe.. Then, "if" the check valve is leaking, the closed Return valve will prevent the spa from draining down. If the spa still drains down, with the Return valve closed, the leak is somewhere other than the check valve..

Thanks,

Jim R.
 
I think your diverter valve on the suction side for the spa is closest to the pump and the pool suction is somewhat restricted the way the valve is pictured and that you also have a single speed pump which has high rpm, may possibly be causing it to pull some flow from the spa eventhough it's in the closed position.
 
Jimrahbe said:
I suggest that your replace the diverter in your Return valve.. Then close the Return valve so that no water flows to your spa return pipe.. With the spa full, shut the system down and see of the spa still drains down..

If the spa does not drain down with the spa return pipe shut off, then open the Return valve and see if the spa drains down.. If it does, the check valve has to be bad.
If the spa drains down with the spa return pipe shut off, then the problem is most likely at the Intake valve.

Thanks,

Jim R.
Click to expand...
Jim, I replaced the internals of the diverter valve today. I replaced the entire door/shaft assembly and o-rings (2 small ones on the shaft and the 1 larger one on the lid) with all new OEM parts. Take a look at the picture below of the old door face gasket and the tear circled in red. Could that tear have caused water to drain out the spa overnight?Compress_20250218_170912_2500.jpg
 
Guy..

I assume this is from your Return valve (Right after the SWCG).. Is that correct or not??

It may or may not be the problem with your drain down, but I suggest that you install the new parts and see how things go..

As a test, do this... Set the Return valve so that the off tab points to the Spa Return pipe.. This will shut off any water going to the spa.. Shut off the pump and let it sit overnight.. If the spa does not drain down, then open the Return valve to let some water go to the spa.. Then shut off the pump and see of the spa drains down.. If it drains down, it means your check valve has to be leaking.

Thanks,

Jim R.
 

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Jimrahbe said:
Guy..

I assume this is from your Return valve (Right after the SWCG).. Is that correct or not??

It may or may not be the problem with your drain down, but I suggest that you install the new parts and see how things go..

As a test, do this... Set the Return valve so that the off tab points to the Spa Return pipe.. This will shut off any water going to the spa.. Shut off the pump and let it sit overnight.. If the spa does not drain down, then open the Return valve to let some water go to the spa.. Then shut off the pump and see of the spa drains down.. If it drains down, it means your check valve has to be leaking.

Thanks,

Jim R.
Click to expand...
Yes, it's from my first return valve right in front of the SWCG. I did replace the parts today. I currently have the valve with the "spa off" and I'm waiting a few hours to see if the water level in the spa drains or not. I'll report back here tomorrow morning.
 
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Jim, here are my findings so far after replacing the internals of the main return diverter valve (door face and the 3 o-rings). I closed off the suction to the spa and the spa was completely full. The spa DID lose about an 1-1.5" of water since yesterday (system was completely shut off during this whole time). Now this is a much slower rate and less water loss than prior to replacing the internals (before it would lose probably 5-6 inches). I didn't do the test yet of leaving the spa open to see if the check valve was bad too since it had already drained a bit even with the spa off. What would you do now? Do you think it could be on the suction side? If so, there are 3 suction lines, two on the pool (from main drain and skimmer that has a diverter valve) and one on the spa (the pool and spa have a diverter valve too). The pool/spa suction diverter valve is right before the pump nearest the filter on the right.

On a side note, I do have a small steady leak (when the pump is on) on the top of my sand filter below where the lide closes. Could this be the problem too? I did buy the o-ring that goes on the lid to replace it and see if the leak stops.

Could the internals of the suction diverter valve (the one to the pool and spa right in front the pump) be bad causing water to leak through the "off" spa position and flow backwards into the pool and skimmer suction lines? See red arrows in photo below. Suction diverter valve circled in green.

Also, could BOTH the main suction AND main return diverter valves internals have been bad and since I replaced one (the return) so far, the rate at which the spa lost water slowed down?
Compress_20250219_155956_6291.jpg
 
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Guy,

If the Spa drained down at all, with the Return valve closed, then the 1.5" leak has to be somewhere other than the check valve... It sounds like you have more than one leak.. Your check valve may still be bad, but with the Return valve closed, the check valve's operation does not matter...

The Diverter valve, right in front of your pump, is called the Intake Valve.. As you said, it allows the pump to suck water from the Spa Drain, or The Pool plumbing (Skimmer Main drain).. A leak here can also cause the spa to drain down, but not as common as the check valve..

The whole system should not have any leaks.. A water leak under pressure will turn into an air leak when the pump is off.. This could cause the water in anything higher than the pool, to drain back into the pool..

Remember from school... when you stuck a straw into a glass of water and if you put your thumb over the end of the straw, the water stayed in the straw.. When you took your thumb off the straw, all the water drained out.. Your pool works the same way.

I would fix the Intake valve and the filter and then see what happens..

Thanks,

Jim R.
 
Jim, I replaced the intake (suction) diverter valve internals like we spoke about. Afterwards, I turned both the return spa off and the suction spa off and then shut the system down completely. The spa was filled to the top at around 9pm that night and when I went check it this morning around 6am it really hadn't dropped at all over that 9 hour period! If anything, it was so very minimal...maybe 1/16" - 1/8" at most which I guess that little bit would just be normal evaporation? If I wasn't actually looking, I would have assumed it hadn't even dropped any at all. Do you think that was the problem all along?
 
Guy,

We don't know yet.. Open the Spa Return valve and see what happens overnight. If the check valve is leaking, the spa will drain down.. If not, then you have fixed it!!

Sounds to me like you had more than one issue..

Thanks,

Jim R.
 
Thanks Jim! Ok, so it sounds like it was definitely the intake diverter valve that was bad AND possibly the check valve. I will open the spa return up like you and keep the suction spa closed off and see if it drains down overnight. I'll report my findings.
 
Jim, I opened the spa return last night and shut everything down. Woke up this morning and the spa was the same level and did not drain down at all...woohooo! So it appears the culprit was BOTH a bad suction diverter valve and bad intake diverter valve (remember...that was a new check valve I had installed recently).
 

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