I only had about 10 tubs of ASFs in my garage last winter so the smell wasn't even noticeable. Now I'm up to 30 tubs of 1.3-1.5 breeders, and another 18 growout tubs full with about 25-30 in each. Counting all of the babies with the breeders, I basically have around 1000 ASFs in my garage.

I spot clean every 3 days and do a full bedding replacement every 2 weeks. This worked out okay over the summer and the smell wasn't bad at all because I could ventilate through the back door. I live in Colorado, so during the winter I will obviously not be able to do this. The oil heater I had running in there last year barely kept the garage within 55-60F.

Lately I've been keeping the garage closed up to test out the smell that we're in for this winter, and after only 2 days post-cleaning it is unbearable. And the smell rushes into the house when the door is opened to the garage.

TLDR version: I need ideas for some sort of system that will periodically exchange the air in my garage without blowing out all of the heat. Preferably something that you yourself are using with success.