What the heck is this plug, plus a bonus

[JimFinn]

This plug is located in my deep end of the pool, below the spillover spa, about a foot under water. Any thoughts on what treasures might lie behind this thing?



Bonus, what do you think this open ended pipe is? Located next to my filter pump return piping (which goes to both pool and spa). I do have 2 bubblers at the bottom of the lounge area in the spa. Not sure if this has anything to do with that.

 

[Bperry]

This plug is located in my deep end of the pool, below the spillover spa, about a foot under water. Any thoughts on what treasures might lie behind this thing?

View attachment 471713

Bonus, what do you think this open ended pipe is? Located next to my filter pump return piping (which goes to both pool and spa). I do have 2 bubblers at the bottom of the lounge area in the spa. Not sure if this has anything to do with that.

View attachment 471714

Impossible to know for sure, but the plugged outlet in the pool might be related to that open pipe. Possibly for an abandoned cleaner.

 

[mknauss]

The open pipe -- does it pull air in when the spa is operating?

 

[JimFinn]

The open pipe -- does it pull air in when the spa is operating?

That's a good question. I noticed some answers you gave to similar questions in old topics, and you mentioned that in your setup, you have an open pipe that supplies air to some kind of bubbler or aerator in your spa? Is that correct?

Until reading that, I always thought a "bubbler" was simply a return nozzle located on the bottom of a spa or pool.

 

[mknauss]

Spa plumbing should be set up that air is pulled into the system to make bubbles at the spa jets. The system is called a Hartford Loop.