[zum14]

Personal preference is external. I like the bean animal but there's a science to the depth of the overflow box and the piping size and where you run the plumbing. My one attempt was a full coast to coast external. It was about 5" deep but didnt run a ton of flow through it. I was able to tune it so the water ran about 1" below the box height. This resulted in a quiet overflow. My current overflow is a 12" deep internal box and the water is running about 2" below the box height. The way I got this tank I had to run the plumbing at the top of the tank and elbow it down to the bottom of the box so unfortunately the water hits the piping and makes quite a bit of noise. It's 1-1/2" plumbing and running about 3000gph. The issue is if you close the gate valve a bit to raise the water height so its quieter it starts running more water down the balance pipe and that makes more noise. Its not just drill and go.