I have a pool with an attached spa. In the spa I have 2 supply lines on the wall that are adjustable. There are also 2 returns on the bottom. The weird pipe is a 2" that comes out of the wall. When we sit in the tub it really does nothing but you can feel cold water inside of it. Is this a balance type of pipe between the pool and the spa? Where do you think it goes from there? Is it just a part of the supply lines to the main pool?