Tool
Something is wrong with my cider — what is it?
Tick what you can detect. 269 signs across 52 recorded faults, ranked by how much of what you describe each one accounts for — then told apart by the one observation that separates them.
Over-pressurised glass fails by shattering. Chill the bottles, do not shake or invert them, move them in a closed crate rather than by the neck, and keep them out of any warm room. If one needs venting, do it behind something, with eye protection, pointed away from you. The full safety note.
Optional, and the single most useful thing you can tell this tool. It moves candidates rather than removing them, because people are often wrong about when a problem started.
Tick everything you can detect. More signs narrow it further, and a sign you are unsure about is better left unticked than guessed at.
Tick at least one sign to see what matches.
Why this gives you a shortlist rather than an answer
Cider faults overlap. Volatile acidity and ethyl acetate arrive together often enough that separating them by smell alone is unreliable; reduction and a sulphite excess both present as sulphur; haze has at least five distinct causes that look identical in the glass. A tool that returned one confident answer would be wrong a substantial part of the time, and confidently.
So this ranks, shows what each candidate accounts for, and tells you what else to look for — the sign that would separate one from the next. Finding it strengthens the case; not finding it weakens it.
Where two candidates end up close together it goes further and gives you the differential: the single observation that decides between that specific pair. Vinegar in the nose against solvent at the top of it. A film on the surface against a clean one. A haze that is getting worse against one that has always been there. Those are what somebody with cellar experience checks, and they are recorded on each fault so that this can check them too.
The timing question at the top is optional and is the most useful thing you can answer. Every fault records the stages at which it becomes detectable — which is not the same as where it was caused, and is the half you actually know. It moves candidates rather than removing them, because people who have just found a problem are frequently wrong about when it began.
It is also worth saying that not everything unexpected is a fault. Cloudiness, sediment, a farmyard note and a marked oxidative character are all normal — traditional, even — in some styles and out of place in others. The difference between a fault and a style feature goes into where that line sits.