Okay! Where'd I leave off? We've got more from
@strange-steve and
@Sadfield emphasising what a can-of-worms yeast attenuation is. I'm glad I've got all that out the way in my last post as it should be obvious how that subject can descend into blazing rows (I've done enough of them in the past!). So here I'm working on mash temperature and fermentability:
Starting with that Brulosophy experiment with high and low mash temp. I read that a while back and immediately fell out with any Brulosophy article as a result. Try mashing brews at 62C and 72C (it is quite feasible to mash at these temperatures; I know because I do it), compare the results and try saying there is no difference!
But it can illustrate what I think is the problem. How does anyone know the mash is at these temperatures?
With "one-pot" solutions the temperature probe is in the space with the element. The system even has a by-pass so you can't be sure the recycled flow is actually running through the mash bed. And if the recycled flow isn't over-flowing into the by-pass, you can get "channelling" (wort taking the line of least resistance) so temperature in the mash bed is inconsistent. So dealing with the first of these issues:
Always throttle back the recirculating flow (I generally halve it) so the by-pass is never in play. The pumps are impeller types and not troubled by throttling the output (with a tap will do, don't
stop the flow though!). The pumps are troubled by throttling the input, but one-pot systems do not have such an option (to my knowledge).
The second issue is harder to deal with. Channelling also means dipping a thermometer into the mash bed isn't very reliable.
Step one is ensure you start with the right temperature throughout the mash bed.
And that means the right strike temperature.
Whoa! I've got controversial! I have a Grainfather one-pot system and it's instructions for use has no concept of "strike temperature" and I assume other systems to be the same (?): It is expected that recirculation will restore the mash temperature in short order. Will it? The thermometer will certainly show a quick return to mash temperature. Reassuring, but is it reflecting the temperature throughout the mash bed? I think not!
It's not difficult to use "strike temperature" with one-pot systems, but it probably requires a bit of imagination to apply it. Once the grain is all mixed and if the strike temperature was well calculated the system should hold that temperature pretty well (
Step two). Critical temperature steps are probably best avoided for the same reason, but a "mash out" is not a critical step (more controversy), just ensure the step has some dwell time to at least try to allow the mash bed to catch up.
Footnote: Where I'm coming from. My "other" system is a 70L 3V HERMS brewery with lots of temperature monitors, so I feel well immersed in the temperature goings on of mash tuns! That said, it has an annoying "feature" of having very slow convergence between set temperature and mash temperature. Working on that just gives me more idea of how to manage mash tun temperatures.
...
... and if that still gets you too low an FG try a bit higher again ... and leave all this calibrating thermometers and trying to understand where temperature differentials emanate from, till when you've got a pint of American Amber/Best Bitter with an FG=1.0010-12, like you want it, in your hand
![BREWING THERMOMETER STICKERS ACCURATELY MONITOR FERMENTING BEER & WINE LIQUID TEMPERATURES 5PCS HOME BREW SPIRITS WINE LCD ADHESIVE [US]](https://m.media-amazon.com/images/I/311DDjo2X3L._SL500_.jpg)
