Oh yeah, great idea to lift the filter a little higher. I will look into it! Its 100 mm so 4 inch-ish. No idea of the brand, I bought it here in Norway 8 years and have been stored unused ever since. I havent peaked underneath that white outer layer either. 

The fan looks like in the picture, no idea what that kind is called really. It is stated to have a capacity of 180 m3 or so. I notice it is removing somewhat less air now but there has alos been no smell outside so all good I guess. And a few more weeks and I should be all done here for now.