Specifically it has to do with this statement in the backwashing instructions in the pool school section
" First make sure that any valve on the discharge line is open and any discharge hose is rolled out to where you want the dirty water to go"
I'm not seeing any valve around the filter area. There's one line that runs to the pump, one that runs to the heater and one more that runs in to the ground. I'm guessing this may be where the discharge water flows but it's no guarantee as I just bought the house. Is it possible there is no valve or discharge hose and it just goes to the ground through the piping?