Is a tight seal on airlock critical?

[dm1217]

I've been using a carboy cap like this:
http://morewinemaking.com/themes/morebeer/thumbs/500x500/product_images/morebeer.com/1/9939.jpg

Should I switch to rubber stoppers, or are these plastic ones fine? I'm concerned that the plastic-on-plastic doesn't give an adequate seal. Or is that nothing to worry about?

 

[ncbrewer]

Lots of times a fermenter bucket lid doesn't seal completely. I wouldn't worry about it.

 

[unionrdr]

That pic isn't very descriptive,but I'd go with the rubber ones. I like a good seal on everything personally,just to be sure nothing can find it's way in & it all works as properly as possible.

 

[billl]

Your beer doesn't need to be sealed. You are just trying to keep the little beasties out. They don't crawl, so anything that keeps them from passively floating into your wort does just fine.

If you plan to store your beer for a length of time, then you'll want somethat with a decent seal just to prevent oxygen exchange.