Water level

[DeepWater]

Are those exposed PVCs connected to the piping that goes from the bottom pond to the top? If so, it seems like they may be a syphon break, so when you turn off the pump, the entire top pond doesn't back-flow to the bottom pond.

 

[Bdun111]

These are 3/4"-1" exposed, open top, pvc pipes that come out of the ground vertically, close to the upper tier water compartments.
There are (2) I know of, and when I blow into them, one of them has bubbles come up from tier with one of the waterfall pvc feeds, the other, from bottom of on lower tier.
And, we experience the back flow to the bottom area, every time.