I'm reading posts and I keep seeing references to brewers opening their vats and others making comments about the horrors of allowing air in. I use 2 Cooper's Kit vats and I open mine and peek in and sniff, all the time. I tap off a hydrometer tube to check SG every day after day 6, then pour it back in (I sanitize my tubes after each use). Am I screwing-up? Is this a poor practice? BTW, I am about to mix my 4th vat worth, in a few days, so I'm not really to "on top of things", and learning what I can from ya'll. Thanks in advance.