New brewer here making first batch of hard cider. I have an airlock on a 1 gallon glass wine jug. Started brewing Lastnight and woke up this morning to foam in my airlock. The foam has gone down in the bottle now so there is empty space in the neck now. It's bubbling away with a bubble in the air lock every few seconds. However there is still a lot of foam in the airlock itself. Is this a problem? Did I lose a lot of yeast that was in the foam and now stuck in the airlock? What do I do to fix this, is it as simple as clean the airlock and out back on? I didn't use the whole pack of yeast, so should I add more? Thanks