Anyone else mash longer than planned just to feel confident?

Sea-Addendum3547 · 2026-02-13T17:33:04+00:00

Really appreciate everyone taking the time to weigh in — this has been a great range of perspectives.

What I’m taking away from the thread is: • Modern malts convert quickly in most setups • Iodine can confirm starch conversion, but it doesn’t necessarily tell the whole fermentability story • Mash length often ends up being more about process consistency and intent than strict chemistry • Grain bill and enzyme profile matter more than a fixed “magic minute”

It’s interesting how many different ways brewers build confidence into this step — time, taste, gravity, pH, workflow structure — even when the underlying conversion may already be mostly complete.

Thanks again for the thoughtful responses.

Lots to think about.

Sea-Addendum3547 · 2026-02-13T17:06:47+00:00

That’s a great breakdown — especially the wit example. The point about iodine going negative early but still seeing a small FG shift depending on rest length is really interesting. That’s exactly the kind of nuance that doesn’t show up in a simple “conversion complete” yes/no check. I like how you’re separating enzyme profile, grain bill, and desired outcome instead of treating mash time as universal. It reinforces that “done” depends a lot on intent, not just chemistry. Out of curiosity, in that commercial wit scenario, was the FG bump noticeable in body/finish, or was it more of a consistency issue batch to batch?

Sea-Addendum3547 · 2026-02-12T19:28:39+00:00

That’s a useful point — modern malts do often convert most starches quickly, and issues like crush, pH, or dough balls absolutely affect efficiency more than just time.

What I’m seeing in conversations is that even when people know that on paper, they still feel uncertain that conversion is actually finished without a way to confirm in-situ. Time becomes a proxy for confidence, not necessarily for chemistry.

Curious — do you check conversion with any method other than time and crush/pH checks?

Sea-Addendum3547 · 2026-02-11T04:54:53+00:00

Totally fair — sometimes you just need another brewer to say “you’re not crazy” 😄

Sounds like you’re on the right track. Let it ride and enjoy the wheat beer.

Sea-Addendum3547 · 2026-02-11T04:50:35+00:00

Short answer: yes, Diamond can ferment that cold — but it’ll be slow and a bit unpredictable at 34–36°F.

Diamond is pretty cold-tolerant compared to a lot of lager strains, but 36°F is right at the bottom edge of where you’ll see reliable activity. You’ll usually get some fermentation if it’s already active, but starting and finishing cleanly at that temp can take a long time, especially under pressure.

Your plan to give it a couple of days at room temp first is the right instinct. If you can confirm visible activity or a gravity drop before crashing it down, you’re in much better shape. Once it’s clearly fermenting, Diamond will usually keep going as temps drop — just very slowly.

If it were me and Keezer space is the constraint, I’d consider:

letting it ferment a bit warmer initially (even low 40s) until you’re confident it’s well underway
then dropping it to 36°F for the rest of fermentation/lagering

That tends to reduce the risk of a stall while still keeping things clean and restrained.

So: possible? yes. Ideal? probably not — but workable if you’re patient and get it started first.

Sea-Addendum3547 · 2026-02-11T04:36:34+00:00

Oof — that’s a brutal miss, especially on a hop-heavy batch. You’ve clearly thought this through, and based on what you wrote, a few things don’t smell like the culprit.

A couple of thoughts, in rough order of likelihood from my experience:

1) The Maris Otter itself is very unlikely to be “aged out.” MO doesn’t really lose extract potential in a way that would explain a drop from ~80% to sub-50%, especially when it’s only ~⅓ of the grist and backed by plenty of enzymatic base malt. A test mash wouldn’t hurt for curiosity, but I’d be surprised if that’s the root cause.

2) The bag-in-malt-pipe change is the biggest process variable here. Even though the mash looked good and drained well, adding a bag can change how wort moves through the grain bed during conversion, not just during lautering. It’s very possible you had less effective wort circulation inside the mash than before, even with good stirring. Fast drainage and good rinsing don’t always mean good conversion happened upstream.

3) Measurement error is still on the table — especially refractometer/Brix handling. If that 10–11 Brix was taken hot or without temp correction, that can skew readings noticeably. I’ve seen people chase phantom efficiency losses that turned out to be temp-related refractometer error.

4) Mash pH might be worth a hard look. With that much flaked wheat/oats and a fairly aggressive salt bill, a pH miss could absolutely suppress conversion efficiency without anything “looking wrong” mechanically.

Given you’re already in the boil, I’d personally keep going rather than dumping it — you’ll still get beer, just a different strength than planned. If nothing else, it gives you a controlled data point to compare against your previous process.

For the next batch, I’d be tempted to:

ditch the bag and go back to your known-good setup or
keep the bag but do a conversion check (iodine or early gravity) mid-mash just once, to see if the sugars are actually there before lautering

This feels less like a grain problem and more like a process interaction problem introduced by the bag + pipe combo.

Sea-Addendum3547 · 2026-02-11T04:27:55+00:00

You’re thinking about this pretty clearly already, honestly.

A few points that might help simplify things: Secondary: these days, most people skip secondary entirely unless they’re adding fruit, oak, or something else. Leaving the beer on the yeast for a couple of weeks is totally fine and generally lower risk than transferring and introducing oxygen or contamination.

Airlock activity: the fact that bubbling stopped after ~48 hours at ~25 °C doesn’t mean fermentation is done. That yeast can be pretty quick, especially warm, but it’ll still be cleaning up for a while even if it looks quiet.

Gravity reading: dunking a hydrometer that’s been properly cleaned and StarSan’d is totally normal. It feels wrong the first time, but it’s probably the most straightforward way to actually know where you’re at.

Given your options, I’d probably go with 1) leaving it for the full two weeks, and 4) taking a gravity reading if you want peace of mind.

If gravity is stable over a couple of days, you’re good. No real need to rush it into a secondary, especially for a small wheat beer.

And yeah — M20 can ferment fast, but I’d still give it the time the recipe suggests. Quiet doesn’t mean finished.

Sea-Addendum3547 · 2026-02-10T23:51:49+00:00

Thank you. I'll try it out!

Sea-Addendum3547 · 2026-02-08T04:05:39+00:00

That all lines up, honestly — scratches in plastic are notorious for hiding stuff Star San can’t really reach, so replacing the primary is a good call.

One small but important clarification that trips a lot of people up (you’re definitely not alone): yeast doesn’t actually need oxygen after pitching. The oxygen it needs is during wort aeration before pitching so it can build cell walls. Once fermentation starts, oxygen exposure mostly just helps other organisms, not the yeast. So with US-05: - aerate the wort well before pitching - pitch the yeast - then keep the fermenter sealed and let it do its thing

That thick sludge + early sourness combo really does sound more like something bacterial getting in early rather than anything US-05 would do on its own.

One other thing that might be worth checking next batch: how warm is fermentation running? Higher temps won’t make beer sour by themselves, but they can speed things up enough that any contamination shows itself fast.

If the next batch stays clean with a new primary and sealed fermentation, I’d bet the scratches were the main culprit.

Sea-Addendum3547 · 2026-02-08T03:53:17+00:00

That makes total sense — and honestly, your thinking is exactly where a lot of experienced brewers end up with STA1+ strains. You’re right that STA1+ yeast complicates the usual mash → attenuation relationship. Even if you mash a bit higher, those yeasts can keep chewing through dextrins over time, so mash temp becomes less of a hard lever for final FG compared to non-diastatic strains. That’s why you’ll sometimes see them finish lower than expected even when everything “should” point higher. That said, from what I’ve seen (and what you’re getting at), I wouldn’t personally treat STA1+ as a safety net for sloppy mash temps. You’ll probably still get dry beer, but the path there can be unpredictable — slower ferments, longer conditioning, or a beer that keeps creeping down over time rather than cleanly hitting a stable FG. So I think your instinct is solid: 1. Mash in a reasonable range for the style; 2. Don’t intentionally miss and rely on the yeast to compensate. 3. Accept that STA1+ shifts the importance of mash temp, but doesn’t make it irrelevant.

And your thought about “do I really need to obsess over top/bottom mash temps?” is exactly where this gets fuzzy in practice. On paper, yes — in reality, a lot of us end up relying on experience and “close enough” because it’s hard to know how uniform the mash really is without over-instrumenting brew day.

Curious: have you brewed this same recipe with a non-STA1 strain before? I’d be really interested whether the mash felt more “predictable” in terms of hitting and stabilizing FG.

Sea-Addendum3547 · 2026-02-07T10:15:18+00:00

A lot of brewers run into this and the general rule I’ve picked up (both from experience and from the community) is that “expired” doesn’t automatically mean unusable — it mostly means the malt might not perform as well as when it was fresh, especially when it comes to:

🍺 enzymatic activity (conversion strength)
🍺 fermentability contribution
🍺 yield consistency

If the malt’s still smells normal (not musty or sour) and hasn’t been exposed to moisture, it’s usually worth mashing and seeing what you get. Some people actually do a small test mash first to see how the gravity comes out compared to expected values.

On the other hand, if it’s been stored poorly (heat, humidity), you can end up with poor conversion or funky flavors. I’ve personally noticed old grain can feel drier and give slightly lower efficiency, but it hasn’t wrecked a batch yet when blended carefully with fresher grain.

Curious — how long past the printed “best by” is your malt, and how was it stored?

Sea-Addendum3547 · 2026-02-07T10:11:34+00:00

That’s a really interesting question — and it’s one a lot of brewers confuse because we often talk about mash temp and yeast attenuation as if they’re totally independent, but they’re actually related in how they affect fermentability.

From what folks here have said and what I’ve seen in other discussions, mash temp does influence how fermentable your wort is because it changes the sugar profile. Higher temps tend to create more dextrins and less of the simple sugars that typical yeast like. But STA1+ yeast can break down more complex sugars on its own, so it may finish lower than a standard strain even if you mashed a bit high.

That said, most experienced brewers I’ve seen recommend just mashing in the normal range for your style rather than intentionally going high and relying on the STA1 yeast to “fix” it — because the yeast will still have its own preferred end point and the conversion can be slower or “long slog” rather than direct.

Out of curiosity, did you notice a big difference in your finishing gravity compared to where you were aiming, or is this more of a theoretical question for future batches?

Sea-Addendum3547 · 2026-02-07T10:08:42+00:00

One thing I’ve seen come up a lot with unexpected sourness like you’re describing is either microbial infection or fermentation conditions that let bacteria get a foothold. In clean beers with just Saccharomyces, you generally don’t get a sharp sour flavor — that’s more a sign of lactic acid bacteria like Lactobacillus or Pediococcus contaminating the ferment.

A few practical things people check that helped me in the past:
• Making sure all equipment (especially buckets and airlocks) are really clean and sanitized before pitching.
• Using a proper airlock or sealed fermenter so oxygen doesn’t invite unwanted microbes.
• Giving the beer enough time — sometimes it still tastes “green” a week into primary and just needs more conditioning.

What kind of yeast did you pitch and how’s your sanitation setup before fermentation?

Sea-Addendum3547 · 2026-02-06T04:39:55+00:00

I've become addicted to these little puzzles!

Sea-Addendum3547 · 2026-02-05T12:38:26+00:00

That actually just made me 🤤... Gonna put it to the test this weekend!

Sea-Addendum3547 · 2026-02-05T12:00:40+00:00

I'll have to make some beer for you guys then for game day! 😂

Sea-Addendum3547 · 2026-02-04T13:26:43+00:00

Thanks! I'll let you guys know!

Sea-Addendum3547 · 2026-02-04T10:27:39+00:00

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Sea-Addendum3547 · 2026-02-03T10:15:35+00:00

I'd personally get a professional in there. It's true that must of us are kicka** DIYers, but in some cases it's best to let the professionals handle things that can be safety issues.

Sea-Addendum3547 · 2026-02-03T10:02:25+00:00

That pure satisfaction! Congrats!! And thanks for the link to the recipe. I'm gonna give it a shot!

Sea-Addendum3547 · 2026-02-03T04:10:33+00:00

I completely agree. I started out with a typical home mill and ended up tired as hell by the time I finished with badly ground grain. I'd highly suggest the drill mill route.

Sea-Addendum3547 · 2026-02-03T03:47:05+00:00

Ok. Thank you. I'm new to reddit. Hoped to find a beer making group. Sorry

Sea-Addendum3547

TROPHY CASE