Guidelines for use of Potassium compounds for pH control

[jrdewhirst]

I'm new to the forum but have been making mead for 5 years. I think I have the process down pretty well for what I do, which is simple -- a totally dry mead with ~12% ABV.

I have tried to pay close attention to water quality. For example, I stopped using my well water in favor of distilled water to which I add minerals as needed. As part of this process, I add Dipotassium Phosphate to ensure >300 ppm of K for buffering. I assume maybe 50 ppm in the honey itself after dilution -- 16 lbs of honey plus 5.33 gallons of water for roughly a 6.5 gallon batch. Usually the mix starts out at a pH of 4-5 but then after the Dipotassium Phosphate is added and the ferment proceeds, it rapidly drops to the mid 3's. With no intervention, it will usually drop below 3.2.

To prevent too low pH during the ferment, I add small daily increments of Potassium Carbonate or Potassium Bicarbonate. I've gravitated to K Bicarb (vs Carb) because (1) it seems to taste less sharp, and (2) it elevates pH more per unit of K.

My question is: Are there guidelines for the use of these compounds? I believe that they are all safe to consume in the modest quantities I'm using (e.g., 16 g Dipotassium Phosphate, maximum 20-25 g Potassium Bicarbonate per 6.5 gallons), so I am mostly focused on other issues. Specifically, is there a taste threshold that I should be concerned about? Anything else?

I realize that K can impact blood pressure (tend to lower it), but I'm not concerned based on what I think I know. My total added K, even including some KMB and sorbate, maxes out at ~1000 ppm ignoring any offset from precipitated solids. 1000 ppm would equate to 1000 mg per kilogram would equate to 1000 mg per liter vs a daily dietary requirement of almost 5000 mg. So I could get almost my daily requirement by drinking a gallon, but then I would puke.

Thanks!

p.s. I tried searching for an answer before posting, without success. Feel free to point me toward prior answers that I missed.

Report

 

[Squatchy]

So a few things. You really haven't let us in on your procedure, so it's all a guessing game at this point. First off. It's bad science when people say yeast stops assimilating ETOH once the pH drops to 3.2. Every strain is different. But I have never had a mead stall for this reason. I've made several 100 gallons, using 30 some different strains. I'm unsure why you would guess how many ppm you naturally find in honey! Distilled water is not good at all for making mead. Well water should be much better suited for this unless it taste foul.. You did say you add minerals. What exactly do you add, and at what ppm? And where did you find this info?

You do need to feed your yeast nitrogen. Preferably organic. You can use synthetic, but most people stopped doing that several years ago due to better science. There are other ingredients that most of us use to rehydrate our yeast with. In doing so, you are gut-loading that straight into the yeast cell at the proper amounts, along with the proper ingredients. When you use what most people use these days. You are giving the yeast the most modern science available. This then keeps the pH from dropping at all. And if you have a naturally low pH, it buffs the yeast so well that they haven't stalled out, going under 3.2 in my experience. However, I have never seen a pH lower than 3.

I want to help. But more info would be necessary. Can you share a recent log?

 

[jrdewhirst]

Thanks. I realize that I didn't give complete detail but that was because I only wanted feedback on a narrow question re potassium. More seemed a probable distraction. Nevertheless, here goes . . .

1. My thoughts on minerals in water come from Water: A Compete Guide for Brewers by Palmer and Kaminski. It's targeted at beer brewers but I think the insights on what's healthy (or not) for yeast generalize.

2. My well water comes with high quantities of iron and slightly high NaCl due to proximity to the sea. These levels can vary depending on recent rainfall, drought. To protect copper pipes, we demineralize the well water. As a result, the iron disappears (and levels of other minerals get quite low) but some NaCl remains. To get to a targeted level of Ca, I'd prefer to use CaCl which is very soluble but then Cl gets higher than I'd prefer. It seemed easiest to start with distilled water and add minerals consistent with #1.

3. My additions and targets per 6.5 gallons are: 9 g CaCl, 100 ppm Ca, 150 ppm Cl; 10 g Mg Sulfate, 40 ppm Mg; 0.09 g Zn Gluconate, 0.5 ppm Zn; plus the K.

For potassium, I start with 16.4 g Dipotassium Phosphate, 300 ppm for buffering. Then small occasional 2.5 - 5.0 g increments of Potassium Bicarbonate up to ~20-25 maximum total as needed for pH control, roughly 500 ppm at max. Plus some KMB and Sorbate. But total K probably stays near or below 1000 ppm.

4. Yeast is 58W3. Temp is 63-68 F. pH is generally maintained at 3.2 - 3.6. Twelve days in a closed bucket then siphoned to a carboy. At these temps, pH and fert there are normally no problems with sulphur, whether as gas or compounds. No fusel alcohols or other issues.

5. Fert is GoFerm (8 g) at hydration then Fermaid O as required, added in daily increments of ~2.5 - 3.0 g over 12 days plus an extra ~4 g at 70% completion, roughly 45 g total. No inorganic fert. YAN requirement is calculated based on starting Brix (usually 22-23); YAN requirement is estimated at ~220.

6. Goal is a totally dry mead, SG = 1.000 or slightly lower. This goal is generally achieved.

Enough for now, I hope. Let me know if you need other details.

I appreciate your comments re good science. Suggestions welcome.

 

[Squatchy]

Hi

Personally, I think that the reason beer brewers build their own water. Is, as you know. They are trying to clone a particular beer from a specific part of the world. And yes. as you know. The water profile can make a significant difference if trying to clone a style.

As a general rule thumb, just speaking generically now. I teach people not to add anything unless they need to. I never see much of a drop when using the adjuncts you are using. And that was what I would have suggested if you weren't already using those compounds. So, I never add any buffers or acids to anything at the beginning of the fermentation. I find it best to tweak the final flavor profile once the mead has been around for a while. It goes through some changes early on. I look at it like a cosine. When it's green, it has a large closing that gets smaller over time and eventually turns into a flat line. I think if you don't wait at least for a long enough period for it to settle down. You might be just chasing your tail.

I did a lot of A/B comparisons using different artesian waters to see which one I liked the best. And now I almost exclusively use the same water, just by chance. But it comes from near buy, and I can buy the 5 gallons of plastic carboys at the store.

There are podcasts from Gotmead. I have several. You might find it interesting to look at the ones that help people to learn how to marry "the best choice strain" with the honey profile. And then, secondarily. Also, consider the other adjuncts in the mead. If you find "Gotmead" podcast. Look at the last quarter of 2017, and you will it there.

Welcome to the community

 

[jrdewhirst]

So back to my original question about the concentration of potassium. It is a mineral required for good health. So I'm not concerned about health risks at the levels I'm using . . . .But is there a taste threshold that I should be concerned about? Anything else?

 

[Squatchy]

So back to my original question about the concentration of potassium. It is a mineral required for good health. So I'm not concerned about health risks at the levels I'm using . . . .But is there a taste threshold that I should be concerned about? Anything else?

Hi. No Idea. I never need to use it

 

[jrdewhirst]

Well, I gave up on the lazy man's strategy of getting an answer here so I adopted another more demanding strategy -- conduct my own taste tests.

As background, the book on Water mentioned about indicates that the taste threshold for the Chloride ion is ~200-300 ppm. My well water tested at ~300 ppm, which is one reason why I moved to distilled water with deliberately added minerals. That volume also suggests that the threshold for the Potassium ion is ~ 500 ppm. That was a concern for me because I routinely add enough Dipotassium Phosphate and Potassium Bicarbonate to exceed that threshold, in total.

So here's the taste test:

1. I poured 1000 g of water (1 liter) into a container and then added 1 g of Dipotassium Phosphate. 1 gram per kilogram equates to 1000 ppm. Neither I nor my wife could detect a taste.

2. I then repeated the procedure with Potassium Bicarbonate. AgaIn, no taste.

3. I then repeated the procedure with Potassium Carbonate. Once again, no taste.

4. Finally, I repeated the procedure with Sodium Chloride (table salt). This time my wife and I could make out a slight salty taste. My assumption is that I would have gotten a similar result from Potassium Chloride, which is why I don't use it. I have to guess that concern about Potassium >500 ppm is an erroneous generalization from the impact of Potassium Chloride.

Recall that my dose of Potassium Diphosphate for buffering is ~2/3 gram per liter and my maximum dose of Potassium Bicarbonate for pH maintenance is ~1 gram per liter. I feel quite confident now that at these concentrations, these additions have no discernible impact on taste.

 

[Squatchy]

Well. Isn't that nice. That's what you should have done to start. Especially id you had all that stuff on hand. You won't earn any points here with an attitude like that. Maybe a beer forum would be better?

 

[darigoni]

Well. Isn't that nice. That's what you should have done to start. Especially id you had all that stuff on hand. You won't earn any points here with an attitude like that. Maybe a beer forum would be better?

Hi Ryan,

You may want to re-read his last post. There was no attitude and we/you should be encouraging posts and posters like this. It’s been a few years since Gotmead was relevant and I don’t think we should be discouraging new members.

dave

 

[Squatchy]

So I may have misunderstood your opening sentence, jrdewhurst. If I did, I am sorry. I will take Dairgoni's word for it. It seemed to me you were being disrespectful of the site and to my help, or, lack of help, perhaps according to you. We just don't build water when making mead. There are no meads that we try to remake in the world due to a long-standing history like there is in brewing. So there is no reason to make an existing water structure. We can't even copy someone else's mead even it they gave us every piece of info available to us to copy.

In 2018, a good friend and I did a 20-batch A/B test. In doing so. We even made a single must large enough so that we each had enough must to go to our homes and make 10 batches each. All things equal, except the yeast strain. And we then made 3 more each. Using the same yeast as well in those. We wrote up and agreed on the same protocol. And did all things the same as best as humanly possible.

After a year or so, four of us met, and we all judged them as if they were in a contest. We had a wonderful amount of meads to taste and see how each strain was different. Based on the yeast strains' contribution.

The interesting thing we learned when we compared the 3 batches that each of us made was Is that even using the same must and protocol. My meads had a "house culture" that was different than Jim's "house culture." Both of our meads were made exceptionally well. And had zero flaws at all. And yet. There was a distinct difference between my meads and Jims'.

So this shows evidence that the things we can't write down things on paper. The simple way we handle things, the timing, the slight variable of things one would not even consider as something that would make a difference would/could add up to marginal differences. We were even aware way back then that even if you made 5 batches, each of the same stuff. Just the size of the vessel would make a difference. We did use the same vessels. And weighed our adjuncts and everything else we could think of. Still left some difference at the end of the day.

A few years ago, I made 2) six-gallon pyments. Each was exactly the same except for the temps each batch was run at. Both were in Controlled environments with exact temp control. There were definitely differences between the two separate batches. I aged them side by side for a year. Along the way, I tasted them and took good notes. At 1 year, they almost tasted the exact same. $-5 months later, no one could taste the difference between the two batches. So I blended them together. Stuck them in a barrel and barrel-aged them. There was no reason to keep them separate. This has caused me to reconsider certain things we used to think were going to have a lifelong effect on meads. I did the same thing two more times. Just to see if the first test was an outlier somehow. It wasn't. And that has caused me to do certain things differently since then.

Sorry, I couldn't tell you the differences in PPM. I have never had to do any of that because I have never had a stall. And it's untrue that a pH less than 3.2 will cause a stall as well. At least, it's not true when using modern protocol. That may have been true before Go-ferm and Fermaid-O came along. I was one of the very first to start using those adjuncts. And had only made 30-40 gallons of mead before that. None of which stalled either.

One thing I always suggest to beginners is. And insist on when I am working personally with students. It is for everyone to taste every exact thing they put in a mead.
And with everything. I have them add some, enough that it goes beyond what is optimal. And this way. Not only do you learn by adding a little at a time and seeing how that unfolds, but when you go beyond the proper amount. Know you have also learned what too much tastes like.

Is there a reason you feel the need to buffer to control a meads destiny before you even start?

Thanks Dave. I'm glad you brought this to my attention. It's hard to understand written verbiage when we don't get the other 90% of the communication that happens when we talk in person

 

[darigoni]

Good reply Ryan. You still have a “fastball”!

I made the same mistake, when I first read his message. When I went back and re-read it, I realized he was actually poking fun at himself, by naming himself the “lazy man”. I was actually impressed that he took it upon himself to do some testing and then report on his findings.

I miss all those members who used to chime in with their collected experiences. It’s amazing how quickly the Gotmead forum went from being vibrant to a ghost town.

Dave

 

[Squatchy]

Yea. It was great fun back then. It was fun when we were on "a learning curve." I don't make near the amount of mead I used to. And I don't really have any gaps in my first-hand experience any more. So I'm not driven to do all the testing I did when I was figuring things out. And to be honest. I have way too much mead sitting around now. I'm kinda like that. When I really get into something. I scream up the learning curve at breakneck speed. Find myself in an elite group of masters. Things plateau at some point. I get bored and move on to the next challenge. I've done this with many things over my lifetime. If only I could end up finding something that I could earn money as fast as I spend it. I am a master of lots of cool things. But every one of them costs tons of money. And the world at large can't even appreciate what kind of accomplishments I have made. So I constantly move from one mistress to the next. Full of passion and desire. Burn the place down to the ground. Find myself "slow dancing in a burning room". Walk away broke and alone. And then start the whole damn thing over and over. A cat only has so many go around. I'm getting short my friend!

And what a ghost town it is. No one has the attention span, and the dedication to working hard to actually learn something anymore. People live with a 20-second attention span. Want to be spoon-fed. Just look for a quick answer. And flip the page to the next post. I got tired of Facebook and just left the entire community in a minute. I still teach people privately, and love that. Look at this when I get a notification. Make mead for special occasions and for gift-giving seasons. Refill my whiskey barrels once they need to be drained and refilled. And that's about it. I doubt I will ever enter a competition again. Unless I go incognito. Could care less about that. So. The band stopped playing and I moved on to play in another band for a while.

 

[jrdewhirst]

Hi Ryan,

You may want to re-read his last post. There was no attitude and we/you should be encouraging posts and posters like this. It’s been a few years since Gotmead was relevant and I don’t think we should be discouraging new members.

dave

Thanks for clarifying. Yes, I was poking fun at myself.

 

[Squatchy]

Thanks for clarifying. Yes, I was poking fun at myself.

Welcome to got mead. If you search for the Got Mead podcast and start at 9/5/17 you can learn modern protocols while you walk through the entire process of making mead from start to finish.

 

[jrdewhirst]

So I may have misunderstood your opening sentence, jrdewhurst. If I did, I am sorry. I will take Dairgoni's word for it. It seemed to me you were being disrespectful of the site and to my help, or, lack of help, perhaps according to you. We just don't build water when making mead. There are no meads that we try to remake in the world due to a long-standing history like there is in brewing. So there is no reason to make an existing water structure. We can't even copy someone else's mead even it they gave us every piece of info available to us to copy.

In 2018, a good friend and I did a 20-batch A/B test. In doing so. We even made a single must large enough so that we each had enough must to go to our homes and make 10 batches each. All things equal, except the yeast strain. And we then made 3 more each. Using the same yeast as well in those. We wrote up and agreed on the same protocol. And did all things the same as best as humanly possible.

After a year or so, four of us met, and we all judged them as if they were in a contest. We had a wonderful amount of meads to taste and see how each strain was different. Based on the yeast strains' contribution.

The interesting thing we learned when we compared the 3 batches that each of us made was Is that even using the same must and protocol. My meads had a "house culture" that was different than Jim's "house culture." Both of our meads were made exceptionally well. And had zero flaws at all. And yet. There was a distinct difference between my meads and Jims'.

So this shows evidence that the things we can't write down things on paper. The simple way we handle things, the timing, the slight variable of things one would not even consider as something that would make a difference would/could add up to marginal differences. We were even aware way back then that even if you made 5 batches, each of the same stuff. Just the size of the vessel would make a difference. We did use the same vessels. And weighed our adjuncts and everything else we could think of. Still left some difference at the end of the day.

A few years ago, I made 2) six-gallon pyments. Each was exactly the same except for the temps each batch was run at. Both were in Controlled environments with exact temp control. There were definitely differences between the two separate batches. I aged them side by side for a year. Along the way, I tasted them and took good notes. At 1 year, they almost tasted the exact same. $-5 months later, no one could taste the difference between the two batches. So I blended them together. Stuck them in a barrel and barrel-aged them. There was no reason to keep them separate. This has caused me to reconsider certain things we used to think were going to have a lifelong effect on meads. I did the same thing two more times. Just to see if the first test was an outlier somehow. It wasn't. And that has caused me to do certain things differently since then.

Sorry, I couldn't tell you the differences in PPM. I have never had to do any of that because I have never had a stall. And it's untrue that a pH less than 3.2 will cause a stall as well. At least, it's not true when using modern protocol. That may have been true before Go-ferm and Fermaid-O came along. I was one of the very first to start using those adjuncts. And had only made 30-40 gallons of mead before that. None of which stalled either.

One thing I always suggest to beginners is. And insist on when I am working personally with students. It is for everyone to taste every exact thing they put in a mead.
And with everything. I have them add some, enough that it goes beyond what is optimal. And this way. Not only do you learn by adding a little at a time and seeing how that unfolds, but when you go beyond the proper amount. Know you have also learned what too much tastes like.

Is there a reason you feel the need to buffer to control a meads destiny before you even start?

Thanks Dave. I'm glad you brought this to my attention. It's hard to understand written verbiage when we don't get the other 90% of the communication that happens when we talk in person

Yeah, you did misunderstand. Dave got it exactly right.

Re buffering, what I've read suggests that pH can be very unstable if the mix lacks sufficient minerals. One way to ensure sufficiency is to have >300 ppm of potassium. Also, my initial 4.5 g dose of KMB is reportedly most effective if pH is low. Adding an initial 16 g of Dipotassium Phosphate kills these two birds -- it provides the required 300 ppm of K and it also tends to ensure an early drop in pH to levels that enhance the impact of KMB.

It may well be that some deviation from my protocol (e.g., higher temps or lower pH) may not always cause problems. But I'd prefer a wide margin of error. Stressed yeast are more likely to produce foul tastes -- sulphur compounds, fusel alcohols, etc. -- that I'd really like to avoid. I don't mind a little extra effort if I can be very sure that my yeast will be happy.

 

[4give]

Thanks. I realize that I didn't give complete detail but that was because I only wanted feedback on a narrow question re potassium. More seemed a probable distraction. Nevertheless, here goes . . .

1. My thoughts on minerals in water come from Water: A Compete Guide for Brewers by Palmer and Kaminski. It's targeted at beer brewers but I think the insights on what's healthy (or not) for yeast generalize.

2. My well water comes with high quantities of iron and slightly high NaCl due to proximity to the sea. These levels can vary depending on recent rainfall, drought. To protect copper pipes, we demineralize the well water. As a result, the iron disappears (and levels of other minerals get quite low) but some NaCl remains. To get to a targeted level of Ca, I'd prefer to use CaCl which is very soluble but then Cl gets higher than I'd prefer. It seemed easiest to start with distilled water and add minerals consistent with #1.

3. My additions and targets per 6.5 gallons are: 9 g CaCl, 100 ppm Ca, 150 ppm Cl; 10 g Mg Sulfate, 40 ppm Mg; 0.09 g Zn Gluconate, 0.5 ppm Zn; plus the K.

For potassium, I start with 16.4 g Dipotassium Phosphate, 300 ppm for buffering. Then small occasional 2.5 - 5.0 g increments of Potassium Bicarbonate up to ~20-25 maximum total as needed for pH control, roughly 500 ppm at max. Plus some KMB and Sorbate. But total K probably stays near or below 1000 ppm.

4. Yeast is 58W3. Temp is 63-68 F. pH is generally maintained at 3.2 - 3.6. Twelve days in a closed bucket then siphoned to a carboy. At these temps, pH and fert there are normally no problems with sulphur, whether as gas or compounds. No fusel alcohols or other issues.

5. Fert is GoFerm (8 g) at hydration then Fermaid O as required, added in daily increments of ~2.5 - 3.0 g over 12 days plus an extra ~4 g at 70% completion, roughly 45 g total. No inorganic fert. YAN requirement is calculated based on starting Brix (usually 22-23); YAN requirement is estimated at ~220.

6. Goal is a totally dry mead, SG = 1.000 or slightly lower. This goal is generally achieved.

Enough for now, I hope. Let me know if you need other details.

I appreciate your comments re good science. Suggestions welcome.

Hi and welcome jrdewhirst.

It's been a long time since I've considered using potassium bicarbonate for PH control. I did at one point find a dosing calc, but have no idea where that is at this point. You can use whatever water you want to, but I don't use distilled water, or tap water treated with chlorine. I'll use filtered water that doesn't filter out most minerals, or I'll go buy the same water from the store - I prefer the artesian or spring water. Denard Brewing (the BOMM) has recipes where potassium is used up front, but I never saw a need for it with today's rehydration protocols and nutrients.
Once upon a time in what seems like a long time ago - heck, maybe it was a long time ago if it was 2019 or so (LOL) - Squatchy talked me off the ledge when I had a ferment going with a PH of 2.8. It wasn't stalling, and didn't.

@ All - sorry I don't get out here that often to participate. Sometimes I come out here to check and folks have already pretty much replied with what I would say (or better).

 

[jrdewhirst]

Potassium and pH in Mead

beerandgardeningjournal.com

This article may have gotten me started on this track. Note my comment (Joe D) among those that follow the article.

Of course, the focus is pH. I think I've sorted the chemistry. My question in the OP was about taste and/or any other issues I may not have contemplated.

 

[Chevette Girl]

Unfortunately, if the question is about taste, it is really subjective, and you ended up taking the correct course of action, trying it out yourself.

Take sulphites as an example. some people can't taste it well past the recommended amounts and some people can taste it way before.

Ulitmately, you will find what works for you and makes what you want to drink. Always be open to new methods, but finding something you really like and sticking with it is not the worst, if you're getting consistent and desired results.

 

[jrdewhirst]

Unfortunately, if the question is about taste, it is really subjective, and you ended up taking the correct course of action, trying it out yourself.

Take sulphites as an example. some people can't taste it well past the recommended amounts and some people can taste it way before.

Ulitmately, you will find what works for you and makes what you want to drink. Always be open to new methods, but finding something you really like and sticking with it is not the worst, if you're getting consistent and desired results.

Yeah, I get that. Not only is taste somewhat subjective but I'm sure we would also find interpersonal variation in the sensitivity of taste buds, measured objectively with recordings of neural impulses.

If possible, I'd prefer just to be careful. So for example, if somebody reports good data showing that the average taste threshold for Chloride is 300 ppm, but 99% of people can taste 400 ppm and 1% can taste 200 ppm, then I'd probably target 150-200 ppm.

So I'd be very pleased to find good data on taste thresholds for common ions (e.g., NA, K, Ca, Mg, Cl, C03) expressed as an average and a range. And any other potential adverse impact of high levels (e.g., Mg >125 ppm is a laxative).

 

[jrdewhirst]

@Squatchy --

<< Is there a reason you feel the need to buffer to control a meads destiny before you even start? >>

More on this question.

Continuing to explore here, I re-read your thread (sticky, above) on overfeeding yeast. The thread includes a post with a 2015 article by Ken Schramm that makes following comments re potassium and pH:

<< Minerals are also a large part of the buffering capacity of must. Clayton Cone notes that potassium levels above 300 ppm are critical to maintenance of pH levels. Haydak et al reported levels from 100 ppm in light honeys (not enough) to over 4700 ppm in darker honeys (more than enough). The average of 205 ppm for light honeys, however, would predict a substantial shortfall when diluted with water at ratios of 3:1 or 4:1. When potassium levels drop below 300 ppm, pH levels in the cell can drop below 2.7, and metabolic activity will virtually cease. Especially in the case of traditional and show meads, early monitoring of the pH is a wise preventative measure. Bisson also comments on the need to establish potassium levels early, as well as the strong possibility that potassium plays a role in strengthening the plasma membrane’s resistance to ethanol toxicity. >>

The article also notes that phosphate levels can be too low in unsupplemented honey must.

All that implies (1) potassium at 300 ppm for pH buffering, (2) potassium somewhere high to resist ethanol toxicity (my mead is ~12-13 ABV), and added phosphate for healthy yeast metabolism. . . .

So in retrospect now, I'm pretty sure that my decision to add Dipotassium Phosphate at the beginning of the fermentation was a direct response to this article (and a few others with similar comments). Dipotassium phosphate solves three problems simultaneously. And it turns out that you are indirectly responsible.

But Dipotassium phosphate can push pH lower. In my last two ferments, for example, pH dropped from an initial 3.80-4.00 on Day 0, to 3.50-3.60 on Day 1, to ~3.30 on Day 2. As noted elsewhere, I was happy with this result because low pH works synergistically with KMB to fight unwanted microorganisms (a fourth problem solved!). But of course as the fermentation continues, pH will continue to drop, potentially to undesirable levels.

Based on other reading, I decided to set 3.2 pH as a floor, at least until the fermentation was almost complete. The question was how to raise pH when necessary. Many potential supplements are not very soluble, and I did not want high levels of Calcium or Sodium (e.g., Calcium or Sodium Carbonate). My decision to use Potassium Carbonate or Potassium Bicarbonate came a little later. Added potassium seemed a benign choice -- and both are soluble.

Searching documents on water quality last night, I found guidelines for drinking water from the WHO, the U.S. EPA, and the Australian government. None of them has any health or aesthetic restrictions on potassium. Moreover, the reported adverse impact of potassium >500 ppm is confirmed to apply only to potassium chloride. Chloride produces a salty taste when paired with Sodium, Potassium, or Calcium. The Carbonate ion isn't nearly as strong-tasting, so the salty taste of potassium bicarbonate is mild.

Very recently, I read a guideline that potassium should be limited to 1 g/L / 1000 ppm for aesthetic reasons. That's roughly the level I get to by the end of a fermentation, which is why I brought up my question in the OP concerning taste thresholds. But as noted above, I couldn't taste it at 1000 ppm.