Pond Boss Forums INTRO Questions & Observations Sizing an AgriDrain Inline Control Structure

My contractor will be resuming the pond renovation in about 2 months and I am trying to finalize my plans for an overflow. I am 99% sure I will be buying Agri Drain’s “Inline Water Level Control Structure” ( web page ). I like the fact that I can control the water level (weeds, dock maintenance) and drain water from the bottom instead of the top. The pond is about 2 surface acres and will be 12-14’ at the dam with an average depth of about 6’. Also, it is fed mainly by springs and doesn’t get much water from runoff. The pond used to have a spillway pipe of about 6-8”.


Now the question – how should I size the structure? Does a 6” or 8” inlet/outlet pipe sound right? And, as I understand it, the height of the structure (how deep it is below the dam structure) determines where the overflow water comes from and how low I can drain the pond. Do you think I could get, for example, a 6’ structure and use a PVC elbow to angle the inlet pipe downwards to reach further down into the pond? That way I would be drawing off the least oxygenated water and have the ability to drain more water if I ever needed to without buying a more expensive taller unit. Does this make sense?

My suggestions, that might not all be good in Pennsylvania.
Go at least 8".
The top board or gate of the Water level control structure should be placed at the same elevation as your highest water level. Then if you pull out the top board the water falls to the level of the next board, and pull the next board the water falls to the level of the top of the board under it, etc.
On the 6 ft model with all the boards out the water level will fall to 6' below highest water level.
As this structure is buried into the dam back from the water it would be easy to come out say 5' and put in a 22 degree elbow, maybe less, that would angle the pipe into deep water.
I would suggest putting a 12" x 5' perforrated pipe on the end for a strainer. That's a little overkill for the strainer, but if you get the pipe deep you don't want it to plug.

RobA, 99.9+% of the time, the level controls are at maximum, so why not just siphon when you want it lower. you have a pond but even the managed wetlands get run at maximum water all the time.

I like to see the water fall and you miss all of that with the level structure but most everybody misses that.

I like the idea of drawing the silty/lowO2/bottoms. watch out for double wall plastic pipe floating!

regarding the pipe size, the prior pipe was 6 or 8..., if that size worked alot of years...or you could have a 4inch and a well sodded emergency spill way...i like the flexibility of 2 or even 3 oulet/overflows. but how much land does it really drain and how much springs after one of your tropical depressions pass bye.