Guides
Most first-batch anxiety is not knowing what normal looks like. Here is the whole fortnight, with the things that alarm people marked as fine.
By Scooter M.·Published September 1, 2026 · Updated September 26, 2026
The short answer
Days 1 to 3: not much visible, but the pH should be falling. Days 3 to 7: a thin film forms across the surface and yeast strands appear. Days 7 to 14: taste and test until it suits you. The whole timeline stretches or compresses with temperature.
| When | What you should see | Is it normal? |
|---|---|---|
| Day 0 | Sweet tea, a pellicle floating or sunk, no activity | Yes. Buoyancy means nothing. |
| Day 1 | Nothing visible. pH already below 4.5 from the starter tea | Yes |
| Day 2-3 | Faint bubbles at the edges. pH heading below 4.2 | Yes — this is the important part |
| Day 3-5 | A thin translucent film across the surface | Yes. That is a new pellicle. |
| Day 5-7 | Brown stringy strands hanging below the surface | Yes. Yeast. Alarming and healthy. |
| Day 7 | Noticeably tart on tasting. Film thickening | Yes. Start tasting daily. |
| Day 7-14 | Continued souring; the new pellicle thickens and whitens | Yes |
| Day 14+ | Sharply sour, possibly vinegary | Fine, but past most people's preference |
The one thing that is not fine: anything fuzzy, dry and raised above the surface, in blue, green, black or white spots. That is mold, and the batch and the culture both go.
Day 3: has the pH passed 4.2? This is the safety checkpoint. Above it, the batch is still relying on whatever protection the starter tea gave it; below, it has built its own. If it has not moved by day three in a warm room, look at the temperature before anything else.
Day 7: what does it taste like? This is the preference checkpoint. It should be recognizably tart. Sweet at day seven in a warm room means the batch is slow; sweet at day seven in a cold room means the room is the problem.
A strip on the glass and a vial of pH strips answer both checkpoints above. The culture is the third thing, and the only one with no substitute.
Craft a Brew
A four-inch liquid crystal strip that sticks to the glass and reads the liquid rather than the air, which is the distinction that matters.
#ad Price as of October 18, 2026. How this is funded.
Micro Essential Lab
A 0.0 to 6.0 range in 0.5 steps, which puts four separate color matches inside the 2.5 to 3.5 window kombucha lives in — a 1-to-14 strip gives you one.
#ad No live price feed yet, so no number is shown rather than a stale one. How this is funded.
Fermentaholics
A hand-selected pellicle with twelve fluid ounces of mature starter tea, measured against the maker’s own published ten percent rule for a gallon.
#ad Price as of October 18, 2026. How this is funded.
Every row in that table assumes 75 to 85 F. At 70 F, expect everything to take roughly half as long again. At 66 F, a batch can genuinely sit for three weeks looking almost unchanged.
This is not a failed batch and it does not mean the culture is dead. Move the jar somewhere warmer — the top of a fridge, a high shelf, an airing cupboard — and it will usually start moving within a couple of days. Temperature covers the fixes in order of cost.
Nothing dramatic. The batch keeps getting more sour and eventually approaches vinegar. It stays safe — the acidity is the protection — but it stops being pleasant to drink.
A batch that has gone too far is not wasted. It is excellent starter tea for the next round, it works as a drinking vinegar diluted heavily, and it is a good base for a second ferment with plenty of fruit, which brings the sweetness back up.
There is a third checkpoint nobody schedules, which is the day the batch goes past where you wanted it. That is a timing and temperature problem rather than a broken culture, and why your kombucha tastes like vinegar covers the four causes and what to do with the sour batch you already have.
Every day on this timeline assumes the jar is in the right temperature band, and the cheapest way to know that is a strip on the glass. The Fermometer review covers what it reads, what its maker declines to publish, and where to stick it.
Heads up: some links on this page are affiliate links. If you buy through one we may earn a commission at no extra cost to you. It never changes a ranking, and we take no payment for placement. The full version.
Ranked on the published rubric. Every row jumps to that product's full write-up below; the button goes straight to Amazon.
| # | Product | Best for | Score | Price |
|---|---|---|---|---|
| 1 | Craft a Brew Fermometer Adhesive Strip Thermometer A four-inch liquid crystal strip that sticks to the glass and reads the liquid rather than the air, which is the distinction that matters. | Reading the jar, not the room | 7.4out of 10 | |
| 2 | Micro Essential Lab Hydrion 9200 Spectral pH Strips, 0.0-6.0 A 0.0 to 6.0 range in 0.5 steps, which puts four separate color matches inside the 2.5 to 3.5 window kombucha lives in — a 1-to-14 strip gives you one. | Reading kombucha’s actual pH band | 8.8out of 10 | |
| 3 | Fermentaholics Organic Kombucha SCOBY with 12 fl oz Starter Tea A hand-selected pellicle with twelve fluid ounces of mature starter tea, measured against the maker’s own published ten percent rule for a gallon. | A one-gallon first batch | 8.5out of 10 |
#1 · Reading the jar, not the room
A four-inch liquid crystal strip that sticks to the glass and reads the liquid rather than the air, which is the distinction that matters.
Who it is for. Every brewer. This is the cheapest way to stop guessing what temperature the batch is at.
Source: Craft a Brew published Fermometer specification (size, display units, compatible surfaces, operating principle), craftabrew.com/products/fermometer-adhesive-strip-thermometer, fetched 2026-09-01. Comparable-strip ranges from retailer listings, cited as comparisons only.
Skip it if. You want a logged, numeric record. A strip is a glance, not a measurement you can write down with confidence.
#ad Price as of October 18, 2026. How this is funded.
#2 · Reading kombucha’s actual pH band
A 0.0 to 6.0 range in 0.5 steps, which puts four separate color matches inside the 2.5 to 3.5 window kombucha lives in — a 1-to-14 strip gives you one.
Who it is for. Every kombucha brewer. This is the cheapest instrument on the site and the one that answers the safety question.
Source: Micro Essential Lab published product specification (range, 0.5 graduations, 100 strips per vial, packaging), microessentiallab.com/product/hydrion-9200-spectral-0-0-6-0-plastic-ph-strip, fetched 2026-09-01. Strip length from retailer listings.
Skip it if. You need a number to one decimal place for a written record. Buy a calibrated pH meter; strips are for reading a band, not a value.
#ad No live price feed yet, so no number is shown rather than a stale one. How this is funded.
#3 · A one-gallon first batch
A hand-selected pellicle with twelve fluid ounces of mature starter tea, measured against the maker’s own published ten percent rule for a gallon.
Who it is for. Anyone starting a standard one-gallon batch who wants the starter tea measured for them.
Source: Fermentaholics published SCOBY specification (12 fl oz starter tea, 1-gallon dosing, ingredients, certifications) and its published 10 percent starter rule, retrieved 2026-09-01
Skip it if. You are brewing half a gallon. Buy the half-gallon version instead; a gallon’s worth of starter in a half-gallon batch drives the acidity too far, too fast.
#ad Price as of October 18, 2026. How this is funded.
Every specification cited on this page came from one of these documents, retrieved on the date shown against the product it belongs to.
The recipe, the timeline, the failures and the safety questions — answered directly, in the order a home brewer meets them.
The full one-gallon method with real ratios, temperatures and timings — what to buy, what to do each day, and what the two fermentations are for.
Mold is fuzzy, dry and raised; a new pellicle is smooth, wet and flat. The distinction that decides whether to bin a batch, and how to prevent it.
The 75-85 F band, what happens on either side of it, why the jar is not the room, and how to fix a kitchen that sits too cold.
The pH numbers that matter, why a narrow-range strip beats a 1-to-14 one, and how to test a batch without contaminating it.
The four reasons a batch overshoots — temperature, time, starter ratio and a strong culture — and how to use the sour batch rather than pour it away.
An adhesive strip thermometer reviewed on its published specification, the two figures its maker leaves out, and where to stick it.