I do not have a system like yours but what I have read. People use a 2 inch vent on 4 inch and 6 inch drain pipes. Your 12 inch pipe could need a 4 inch vent. It may create so much suction your small vent pipe won't let in enough air to break it. You may be able to buy a saddle fitting to put a larger vet pipe on your 12 inch drain?

61 acre water shed lake. bass, channel cat, black crappie, wiper, walleye, redear sunfish, blue catfish and bluegill. To many bullhead and common carp
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