The fitting that is closest to the sight glass on the left side of the second picture is your Waste line. The line with the 1 on it is coming from your pump so that would be the Inlet side of the MPV. The line below that one, hidden behind it, is going out to your pool, likely through the heater first, so the Outlet line of the MPV.
The smaller 1" line with the shut off valve in the 3rd picture likely goes to a pressure side port for a waterfall or slide?