Your vent is working properly. Only problem is the gas drops in cool evening air and should only be a problem a few months of the year. Unfortunately, the warmer months when you want to be outside. Do not plug the vent as other problems will occur and can be deadly if the gases vent into an unoccupied area and or build up in a basement where a sleeping area is located, or source of ignition. Do not add items such as Rid X to your system. Use only commercial grade enzymes. I am a Lic. Wastewater Operator and service over 100 home treatment units. Contact Consolidated Treatment Systems at 937-746-2727 or email at bennette@consolidatedtreatment.com Ask for product item A4054-12 Lenzyme Bacteria (box) 1 box ? 12 applications It is a dealer item. Tell him A. Wolverton from Shenandoah Environmental Services, Inc. in Virginia referred you to him (I am a dealer). He can either sell the product to you, if not, get you in touch with a rep in your area. Check out these sites also. www.odorhog.com and www.spotfree.net They both make odor reduction carbon filters for your vent. I hope the info helps.