Originally Posted by Yooper
I keep my cider in primary just about 5-7 days. You may have some headspace, even if you don't rack your ciders normally (I do) so I'd make sure it's kept topped up in a carboy even if you don't want to rack it.
Very good point mine had been sitting for about a month but I transferred it to another container this weekend and topped it off with fresh pasteurized apple juice. Took a reading and tasted it. Seems to be done fermenting (finished at about .998), I didn't taste any off flavors from possible oxygen exposure. The apple taste did seem a little muted but hopefully some aging will help enhance it. Thanks for the advice!