I live at 9200 feet I am on my second batch of beer. Both batches did not really chug as I call it.First batch tastes great but no carbonation Second batch yeast rose up but went flat in 1 day just added fishtank aerator. Any suggestions?
At that elevation you're only about 4 psi lower than sea level.
While it would seem wort wouldn't hold oxygen as well for the yeast at that elevation I think it's negligible.
You can always add more oxygen if the yeast seems slugish, but I would stop once you know alcohol is present.
Sounds more like the yeast is stressed from poor nutients, health, or pitch volume.
Edit: let me start again, gratz on your first brews What you're seeing can be normal fermentation, the foam (krausen) will always fall back in. Your beers Carbonation doesn't happen at this point. Carbonation is achieved by adding a priming sugar when bottling, or by force if kegging. Some kits may have a single vessel for fermenting and serving where the fermentor is sealed like a keg when fermentation nears the end.