SPA Water Receding into Main Pool when the Filter Pump is OFF

[Pietro167]

I've been scratching my head on this one. After reading various posts, I performed the following troubleshooting with no resolution:

• Replaced Check Valve
• Done a dye method to see if water is leaking in the SPA only (doesn't go anywhere, maybe to slow to detect)
• Placed valves B and E in the pic below to SPA mode to try to isolate.
• Shutoff valve D which is the waterfall return pressure

I know that there is no leak (Pool or SPA) as the SPA water does go back into the pool and vice versa when the filter pump is ON so we can rule that out. Since the SPA is higher than the pool, laws of gravity will try to level out both bodies of water which is what's happening but there has to be a slow leak within some valve or pump I presume? The receding of the SPA is slow so if I turn off the Filter pump for about an hour, it possibly recedes at a 1/4 inch rate. I've also checked all plumbing for any leaks and it all passes.
Let me know if you can help out with any tips.
I've labeled all the pipes and valves in the pic below for your reference.
Thank you, Pietro

 

[mas985]

The spa/pool suction valve could be leaking. I would inspect the valve internals although it may be difficult to detect any defect.

 

[Pietro167]

The spa/pool suction valve could be leaking. I would inspect the valve internals although it may be difficult to detect any defect.

Thanks for replying. Per my pic, which valve are you referring to? A or B. I labeled them as i’m still learning the pool system!

 

[mas985]

Valve B. That switches between the spa and pool and if it leaks, will drain the spa into the pool via the suction pipe paths.

 

[Fpppool]

Valve B. That switches between the spa and pool and if it leaks, will drain the spa into the pool via the suction pipe paths.

Thanks for replying. Per my pic, which valve are you referring to? A or B. I labeled them as i’m still learning the pool system!

My current case is the actuator valve at the suction (intake) side the one causing the spa water going back in the pool via the main drain (most likely).

 

[Pietro167]

An update. Been busy but finally got to it. I replaced Valve B but it still had the same issue. Going to close the Pool Main drain valve A tonight and see if I can isolate this.

 

[WaynePool]

An update. Been busy but finally got to it. I replaced Valve B but it still had the same issue. Going to close the Pool Main drain valve A tonight and see if I can isolate this.

are you able to resolve the issue yet? My spillover spa has the same problem but I have not identified the cause.

 

[Pietro167]

are you able to resolve the issue yet? My spillover spa has the same problem but I have not identified the cause.

Per the pic below, I finally found the culprit. Bad diverter valve.
First, you have to figure out and understand how the water flows. So I started with the direction of the how pump pulls water then figured out the path. Per the pic below, I have Start in orange which is the suction of the skimmer basket location in the main pool, then the blue arrows show the flow and eventually end at the SPA and POOL returns.
I replaced the diverted valve (brand new one) where the purple circle is thinking that was causing the problem but that did not resolve it. Then I saw that the SPA water receded in SPA mode (see yellow water path) and POOL mode (blue path) so I put my focus on the valve actuator/diverter in the red circle. I took it apart and just decided to swap out the diverter valve with the other one I replaced in the purple section.
Per the pic below I saw some chipping on the left side and the rubber around the diverter seemed to have flattened out a bit. Once I replaced it and put it all back together, the spa did not drain so for me, this valve location was the source of the drainage.
Hope this helps.

 

[WaynePool]

Thank. My diverter was bad too but it was at the intake actuator valve instead.

 

[WaynePool]

Per the pic below, I finally found the culprit. Bad diverter valve.
First, you have to figure out and understand how the water flows. So I started with the direction of the how pump pulls water then figured out the path. Per the pic below, I have Start in orange which is the suction of the skimmer basket location in the main pool, then the blue arrows show the flow and eventually end at the SPA and POOL returns.
I replaced the diverted valve (brand new one) where the purple circle is thinking that was causing the problem but that did not resolve it. Then I saw that the SPA water receded in SPA mode (see yellow water path) and POOL mode (blue path) so I put my focus on the valve actuator/diverter in the red circle. I took it apart and just decided to swap out the diverter valve with the other one I replaced in the purple section.
Per the pic below I saw some chipping on the left side and the rubber around the diverter seemed to have flattened out a bit. Once I replaced it and put it all back together, the spa did not drain so for me, this valve location was the source of the drainage.
Hope this helps.

View attachment 556209

View attachment 556210Did you buy only the diverter as shown in the picture or a complete set? And where did you buy it?