Though hard to see in this photo, there is a black hose attached to a white plastic elbow which allows water to flow into the counter-weight bottle when the water in the flood tank reaches sufficient height.
I made this change because the previous setup was too sensitive. This is less of a surgical solution and more of a “hit it with a hammer” fix. It works really well.
I haven’t gotten the second grow bed tray installed. I’ll get there . . .