It's fine. I assume the beer is still actively fermenting, in which case not only will freshly-produced CO₂ (somewhat) displace the O₂ in the headspace, but the yeast can still clean up any O₂ that does dissolve into the young beer.
Many high-gravity beers actually forcibly inject O₂ during the early stages of fermentation to get a solid ferment.
If the bucket is a mess you should be cautious about using it to ferment in - the main downside to buckets is that easy access to the internal surfaces makes it easy to scratch. Scratches are potentially difficult to clean, and so are a possible source of contamination.
Here is a an article on identifying food grade buckets. tl;dr - look for the recycling ...
After some research I think I discovered a potential source of the problem. Potassium metabisulfite decomposes into, amongst other compounds, sulphur dioxide - a gas which is irritating and toxic at higher concentrations. SO2 reacts with water to form sulphuric acid (nasty!), and that includes water in mucus membranes, which explains why I experienced a a ...
I think Secondary fermentation is a term that came over from wine making. Secondary fermentation in the wine world is where you have the malolactic fermentation happen. This is a bacteria not yeast and it reduces the malic (green apple) acids to lactic acids soften the wine. This usually is done in barrel storage.
Generally green apple (acetaldehyde) is due to fermentation not being complete.
Did you cold crash? Did you verify that your beer was done fermenting?
It is strange that your fermenter builds up so much pressure, even with an airlock attached. Are you filling the airlock to the top or to the line?
Too much CO2 will cause the yeast to slow down, which ...
No problem....I go longer than that in buckets regularly. However, dry hopping is one of the few times I still use a secondary. There are interactions between hops and yeast that can increase flowery esters. After experiencing that, I found that I get better dry hop character by getting the beer off the yeast before dry hopping.
In my opinion, buckets are close to the cheapest part of brewing and you should not take chances. a reputable home brew supply house will sell them for around $15 with a lid and spigot. i would hate to see you spend a day brewing, a day of bottling activity, 2-3 weeks fermenting and a couple weeks in the bottles and find out that you have 2 cases of gross ...
Look for the recyclable marks on the buckets, usually on the bottom. There should be three arrows in the shape of a triangle with a number in the center. If the number is #1 or #2 then it is food grade.
Usually #2 which is HDPE or high density polyethylene.
Two months is not too much, if the temperature is not too hot.
Best scenario, you could be lucky and still have some water in the airlock. Beer might be fine.
Worst scenario, water has evaporated in the airlock. Beer has a great risk of contamination or spoilage.
As for the smell, it will depend on temperature as well. If the airlock is dry and the ...
2 months is fine. Lots of people will leave their beer in a secondary fermentor longer than that. The only issue you'll have is that your beer might be oxidized and taste old because the cheapo plastic bucket fermentors generally aren't terribly air tight and are only good for the primary fermentation. If it was in a carboy or more airtight vessel, it ...
Depending on what bucket you use, it might just be easier to buy a new one. :)
Otherwise, get an unscented soap and wash properly. Rinse, wash again, just to make sure. Rinse well. And verify that you got everything.
You can now use StarSan to sanitize your fermenter. after it has been cleaned.