With the Kansas wind blowing at 35mph for the last two weeks, I'm officially switching to a nipple waterer. I'm tired of all the water being blown away. I've got the nipples ordered, but have one quick question. Do you need a valve at the top of the bucket for air flow? I would think that you do, or you'd run the risk of vacuum lock, but it seems like the all of the ones that I have seen are sealed pretty tight.