Can't Figure Out What Valve This Is

Greetings,

Here is a picture of my pool plumbing.  I just replaced the two check valve covers on the far left.  I am trying to figure out what the valve lever is to the right of the two check valves.  When I turn it off ( handle to the right) I have no air bubbles and my water presure flowing to the pool from the spa is much better.  If i put it in the middle I get some air bubbles in the check valve to the left of the valve handle and the spa has less water pressure flowing into the pool.  I don’t know what that valve lever controls as the writing is long gone and I don’t have a schematic.  Thanks for any help you can lend.

  • Craig Farnham