Spa water draining into the pool

[Goatride]

Hi, new member. Just noticed my spa was draining after pump shutoff, and found this forum. Assuming it's a check valve - pool and all equip just turned ten years old.
there are four check valves in my system, thinking it's the one marked spa bypass in attached photo. You guys think that's probably it? Was going to order just the flap as not to re plumb. Thoughts?
Thanks!

 

[CountryBumkin]

You can certainly replace the check valve innards and not need to re-plumb anything.

Is your spa raised (does it sit higher than the pool water level)?
If yes, then then either the spa drain line or return line to spa could be the problem. Since both the drain and returns (spa jest) would be above the pool water level and therefore can gravity flow back into to the pool if you have a bad check valve.

So if your not sure, you could watch the spa level until it drains to the level of the returns, and then if the water level keeps dropping you will know it the drain line check valve that is leaking. If you have a leaking check valve on the return line to spa then it would only drain until the returns are just above the spa water level.

However without knowing the details of your pool (spa location, plumbing layout, etc.), it's hard to know what's going on with your system.

That's quite a maze of pipes you got there. Looks like a pain to clean out the pump strainer basket.

 

[Goatride]

Yeah it's a pain to do anything back there, but equipment had to go in that cramped space.
I've got to rebuild seals on main pool pump, not looking forward to that.

Spa is above pool but connected. Spa Jets definitely above pool waterline, Spa drain I think below pool line.
As the check valve innards are only $25 a pop maybe I just replace the two upper left (labeled spa bypass and spa jets)?
the spa jets is the one in back connected to the spa booster pump which is almost never on. The spa gets water during the day via the main pool pump spa bypass which has a waterfall/spillway from spa to pool.

- - - Updated - - -

Forgot to mention I'm also seeing de in spa

 

[Goatride]

And here's the spa/pool