How many overflows

[James Bowman]

I am having a 380 gallon tank built. How many overflows should I have on it and returns? Also what size is good?

 

[CC13]

I am having a 380 gallon tank built. How many overflows should I have on it and returns? Also what size is good?

How many overflows? Or how many drains?

I have a large tank and its a peninsula style tank. I have 1 overflow that runs the length that is against the wall and inside the overflow I have two 1.5" drains that go into the sump. One drain is enough to handle any and all water but I can control the flow on each drain with a gate valve and I have tuned it so its silent:

#1 drain - is in full siphon all the time
#2 drain - only a slight amount of water goes into and is always 100% open. Basically the water line rests JUST above the PVC

I can post pictures if you like, it might be hard to visualize but its similar to this.
https://www.reef2reef.com/threads/diagrams-durso-herbie-and-bean-overflows.318087/