It has been awhile since I put together an irrigation plan with a larger distribution system so maybe I am just a little rusty. I am cross checking with my flow charts and showing that a 4" class 200 line can handle 200 GPM in the safe flow rate. However when I have FX run the valve size, it wants to put a 6" class 200 for a flow rate of 125. I know there is some good conservative calculations built into FX, but this seems off and I am not sure what I am missing in the settings.
If someone can steer me in the right direction that would be greatly appreciated. (telling me I have lost my mind is an acceptable answer )