I have read several recommendations to use bleach or baking soda/vinegar to help eliminate sewer odor from drains and wanted to make sure of the appropriate application before sending these chemicals into my system. I have house built in ’39 with a concrete floor basement. Where the main drain line comes down the side of the house in the basement there is 1 foot by 1 foot grilled hole that is what I’m guessing a sewer vent. I am starting to get a strong sewer smell from the vent and have noticed some mold growing on top (it is not in the most accessible spot or I would have noticed earlier). Should I pour bleach down the vent to kill the smell and if so how much would be appropriate? Thanks for any feedback.