allowing air into fermenter

Hey all,

So just finished my latest batch and managed to achieve final gravity all beit only just. I am fermenting in a stainless steel tin with a loose lid ontop. Which is not sealed around the edge air can get it. For the first few days I get great fermentation lots of foam ontop etc but after that it seems to subside and then stops fermenting. I keep it at regular temp.  Could it be that I need to air seal the fermenter?

I would think if the lid fits well you could build up pressure in the fermenter, yeast do not like pressure and you definately dont want air in there during fermentation, yeast likes air during the initial lag phase when they multiply but when they get rocking you want to keep the oxygen out. I have seen people put saran wrap over a bucket and they swear by it. I like the old glass carboy with an airlock myself

What you're seeing is normal. The majority of fermentation occurs in the first four days or so.  After that you're mainly letting the yeast drop out, but an airlock would still be burping every now and again.  Also keep in mind that CO2 is heavier than air, so even if a little air gets in it won't get to the brew.

Sealing it tight would definitely be dangerous.  If the pressure didn't cause it to burst, it could release violently enough to cause injury when you opened it.

Bad idea.