I have a question about my spa. It was installed in 1992 several owners ago so some things puzzled me.
Around the spa are four jet nozzles, when I set the return line to go to the spa, water shoots out from those water jets. I have shown in the picture below the water jets in yellow. However, located higher then the water jets are four openings. they are shown in red. What are those holes for?
There are four of these holes, I have no idea what they are for. Two of them are just round holes, the other two have grid covers on them. During the cleaning process as I sprayed down everything inside the spa, I point a garden hose nozzle into one hole and water (with dirt and leaves) came out another hole, so they are interconnected. The main drain is at the bottom of the spa, so I have no idea what those four holes are for.