Hogfan and gully washer
You are correct! There needs to be a vent to the surface from the 4 inch pipe. I just got off the phone with Rex (Rainman). He will be in touch with me later and a diagram will be posted soon.
Heppy
Roger that - I think that will work. Rereading DC70�s thread, I initially missed this statement: �I ran a 4 inch piece of pipe to the surface with a grate flush with the ground for the air to enter.� Appears that he used this 4� line to equalize the underground chamber pipe to let the water inside raise and lower. Sounds like you are on the right track. Whatever you do, don�t let that surface pipe clog, it could drain the pond before it breaks siphon.
Good luck!
