I've been looking online as best I can, but cannot seem to find an answer. Our inground pool has a Hayward 4 way flow control valve leading into the filter system. It has 1/2 and 1/2 and Full settings on both Port 1 and Port 2. I've figured out that Port 1 is our skimmer and Port 2 is the main drain, so by process of elimination, 1/2 and 1/2 should be running both. Why would there be a 1/2 and 1/2 setting by each Port though?
I'm guessing I need to be running the system set to 1/2 and 1/2, switching to full Port 1 when I vacuum. Is that correct?
I'm guessing I need to be running the system set to 1/2 and 1/2, switching to full Port 1 when I vacuum. Is that correct?
However, you want to keep some suction coming in from the MD when vacuuming so that you don't get TOO much suction causing the vac head to stick to the floor 
(an easy way to know how far to close off the MD side is: hook up the vac and then adjust the valve until you see a 1/2 - 1 psi drop on the pressure gauge