Herbie Overflow

[untamed]

Yes, they make 1.5" gate valves. They aren't too difficult to find.

Your explanation for the sump water level doesn't make sense, though. Is the water from the tank falling into an overflow box? Basically, the amount water that you pump INTO the display tank ALWAYS equals the amount that falls out. It just does.

If you are pumping 400gph into the display tank...and only getting 300gph back into the sump...your display tank would be overflowing!

The key to a Herbie is the fact that a given pipe size will actually handle a variable maximum amount dependent on the water pressure behind it. So if you dial back your Herbie valve, the water in your overflow box should start to rise....but it won't rise forever...as the water behind the valve rises, more pressure is exerted which forces more water down the pipe. This hits equilibrium and the water height behind the valve stays constant.