I ride mostly at Eufaula since we got the lake place. But used to hit Dirty bird, draper and arcadia.
That piece is included with the flush pro kit. I just forgot to use it last time. When you hook up a hose and turn on the water, it has enough pressure to open up the valve. In order to gravity feed/suck anti freeze in you have to manually open the valve, hence the small plastice piece, then connect your hose. I use a five gallon bucket that I attached a small length of garden hose to and set it on the sun deck right above the flush pro.