I built a pond many years ago and this is the way we designed our drain basically , yours is slightly different. We used 6 inch PVC that was basically like an upside down p trap actually shaped more like a rainbow and not quite as u-shaped It ran up the face of the dam on the water side and down the backside, on the waterside we had a 2-inch candy cane basically, and if the water-level ever got up to that candy cane it created a suction, I'm not sure how to explain it, it would blow water out the back side like a firehose.
I built a pond many years ago and this is the way we designed our drain basically , yours is slightly different.
We used 6 inch PVC that was basically like an upside down p trap actually shaped more like a rainbow and not quite as u-shaped
It ran up the face of the dam on the water side and down the backside, on the waterside we had a 2-inch candy cane basically, and if the water-level ever got up to that candy cane it created a suction, I'm not sure how to explain it, it would blow water out the back side like a firehose.
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