If I didn't know the part about the meat fridge I'd just say it sounds like the beer is appropriately fermenting with a healthy yeast krausen and the smell is normal fermentation smells and the "acid" is a big whiff of CO2. If you are pitching dry yeast and there is no yeast carried over from batch to batch it would be nearly impossible to have something in your equipment overtake the yeast that aggressively unless you practice no cleaning or sanitization, which is not the case here, especially if you are cleaning and sanitizing.
I wonder if the problem is one of the chemicals you are using is leaving behind something that is mixing unpleasantly in the beer.