Pond Boss Forums POND CONSTRUCTION Building a dam Overflow pipe size

I am no expert but what your talking about does not set right with me. The pond size is not what you look at for your emergency drain, it is the drain field that drains into it. Pluss the height of the dam above the main spill way pipe which determines the amount of rain your pond will hold before it goes over the top and washes out.
I have heard of using a smaller vertical pipe than the horizontal. To help with clogging. But in my uneducated mind your choking it down way to much. If you have a 8 inch riser and then bell that yet more on top you probably need only an inch bigger horizontal pipe. There is only so much water that can go threw an 8 inch pipe and an 18 inch pipe can take 2 to 3 times that amount.