One of the food-grade solutions available was, I believe, a 100% solution sold in a 100-mL glass bottle. Another was an 85-88% solution sold in a 500-mL plastic container (lifetime supply for a home brewer).

I have highly alkaline water (180 ppm), with a low calcium (60 ppm) content. I use two parts distilled to one part tap water to get the ppm down to a level that I can work with in my mash. The pH of the blended water runs around 6.6, and after grain addition (I primarily brew lighter colored lagers, 8-15 SRM) and 1 tsp of calcium chloride the pH settles in at around 5.4.

I use the same blended water for sparging, but to lower the pH to 5.7 or so I need to use about 200 mL of a lactic acid solution. I use an 88% solution of lactic acid at 2 tsp per 3 cups of water. I would like to switch over to the phosphoric to reduce the chance of off-flavors resulting from the high amount of lactic solution used.

Which type of phosphoric acid is the safest and most effective, and what is the proper dilution rate? What are the best storage conditions for unused phosphoric acid? What precautions should be used when working with phosphoric acid?

A: You're right, 180 ppm of total alkalinity is very high. My water here in Nashville (from the Cumberland River) is only about 60 ppm. Your method of diluting the tap water with two parts of distilled water should give a water similar in alkalinity to mine, but with a very low calcium content. Restoring the calcium content with calcium chloride or calcium sulfate is imperative, and you are doing that. In fact, it sounds like your water treatment program is excellent for the conditions you face with a very difficult water supply.

Changing to phosphoric acid is a good move. It is much stronger and more stable. To give you an idea how little is required, for my water supply I need to use only 1 mL of 75% phosphoric acid for every 3.5 gallons of sparge water. This drops the pH from ~7.7 to ~5.7.

I have never run across a 100% "solution" of phosphoric acid. The two concentrations I have seen are 85% and 75%. Check with your supplier to make sure about that 100%. In any case, even 75% phosphoric acid is pretty syrupy, so assuming prices are comparable I would go for the lower concentration. This concentrated phosphoric acid can be stored at room temperature indefinitely.

Highly concentrated phosphoric acid is corrosive and dangerous (though not quite as problematic as nitric or sulfuric acid). I once spilled a drop of the 75% solution on my skin and found that it took a minute or so for it to start burning. Getting it into the eye, however, could result in instantaneous damage. For that reason I urge you to wear safety glasses or goggles, as well as rubber gloves, when handling the concentrated solution. Always work near a supply of running water, in case a spill requires a quick washdown. And finally, remember the motto of Joe Hale (my high school chemistry teacher): Do what you oughter, pour acid into water! Pouring water into acid can cause bubbling, hissing, and splashing.

Regarding working solutions: In my books I have often recommended making up a very dilute working solution of acid to make measurements easier with the (relatively) small amounts of acid you are dealing with. I suggest a 5% solution, that is, 1 mL of 85% phosphoric acid for every 17 mL of water. Be aware, though, that phosphate is a nutrient, and in spite of the extremely low pH of this dilute solution, something may be able to grow in it eventually. Don't make up more than you can use in a brewing season. The alternative to dilute working solutions is to use a pipette, which is capable of accurately metering very small volumes of liquid

One final suggestion: If you are paying for your distilled water, you may find it cheaper to use straight tap water for brewing. Even though tap water will require three times as much phosphoric acid as your current method, you will probably come out ahead financially. Unless your water has other problems that you have not mentioned (for example, high concentrations of sodium and/or sulfate), flavor should not be affected much by this change. Of course you must regard any such change in procedure as an experiment and use a proven recipe, changing only the water treatment.

As we know, gravity is one of home brewers' best friends. The proper method for using carbon dioxide to move liquid is to have the source vessel above the receiving vessel. When CO2 is injected into the source vessel, the liquid moves up the racking cane and begins to flow into the receiving vessel. Once the liquid begins to flow, a siphon is created. At this point, the purpose of the CO2 is simply to backfill the empty space. If the CO2 were removed, air (and all the nasty stuff it contains) would be sucked into the carboy.

I prefer using carbon dioxide to a vacuum pump because with a vacuum pump air will need to be sucked into the carboy to prevent it from imploding. One other note: I do not use the carbon dioxide setup for putting my beer into bottles. When I bottle, I siphon the beer into a bucket (using CO2 to get the process started), add my priming sugar, and bottle using gravity only. I do agree with you that a CO2 bottle and regulator are well worth the cost.

A: Basically, I agree with your comments. Ideally, beer should be kept under a layer of carbon dioxide or inert gas from the time it begins to ferment until the time it is poured into a glass for consumption. In an imperfect world, however, compromises have to be made, usually because of what things cost. A typical homebrew fermentation vessel is not built to withstand pressure, positive or negative. When you use carbon dioxide to push beer out of a carboy it is true that once the beer starts flowing by gravity, the only purpose of the CO2 is to backfill the container as it empties. The danger I see is - especially with an unregulated source of CO2 pressure - that pressure may build up in the fermentor and cause it to explode.

One idea I did not mention in my original answer is that, if you insist on using carbon dioxide to start a siphon and backfill your nonpressure fermenting vessel, you could wrap it up with burlap or other heavy fabric and duct tape. That would avoid the fragmentation-grenade effect if, despite all your precautions, you did manage to blow up your carboy.

I have seen no IBU calculation formula that a home brewer can use to approximate IBUs in boils of less than 5 gallons. Is there an easy way to determine IBUs in boils of this volume (plus taking into consideration the additional water added to make up the final volume) that doesn't require pages of arcane math?

A: The formulas I have seen are not based on a specific gallon figure; wort volume is something you have to plug in. But that may not be what you are referring to. It sounds like you are talking about the effect of high wort gravity on hop utilization (isomerization of humulone).

To this question I can give an approximate answer. If your original gravity (after dilution) is about 1.050, you are boiling your wort at about 1.085. That gravity is high enough to make a significant difference in hop utilization, but not a huge difference. Based on my brews with some barleywines of about 1.085 original gravity, I would estimate utilization at this gravity to be about 10-15% lower. For example, instead of 30% utilization for the boiling hops, I got about 25-27%.

The easiest way to adapt a formula designed for full wort boils would be to just go through all the calculations using 6 gallons as the wort volume and then multiplying the estimated IBU result by 0.85 or 0.9.

Note, however, that some IBU formulas have a calculation to compensate for wort gravity. If you use one of those formulas, use the true batch volume, but calculate IBUs based on the gravity of the wort at boil rather than the original gravity.

As you may know if you've been reading BT for a while, I'm a skeptic when it comes to IBU formulas. None of the ones I have used has been that helpful. In any case, you end up having to fine-tune the hopping schedule to get the flavor balance you are looking for.

A: What you were told is basically true. We use Wyeast #1056 (Wyeast Labs, Hood River, Oregon) for most of our ales. The reasons are purely pragmatic, and they illustrate the kinds of compromises you have to make when you get involved in commercial brewing.

The first reason is the difficulty of maintaining a number of yeast strains. Most brewpubs do not have the equipment needed to propagate yeast outside the fermentors. Their basic method of yeast maintenance is to repitch yeast from the bottom of one tank into another. With unitanks, this is easy to do, and the yeast is being held under a layer of cold beer, which is the best way to store a yeast slurry. Even this storage method has its limits, though; you always want to pitch a slurry that is as fresh as possible. Personally, I would never pitch yeast from a beer that had been brewed more than two weeks ago, and 10-day-old yeast is better.

Unless you have a lot of fermentors, using several strains of yeast for different styles of beer can pose problems, particularly if one or more of your strains is used only for a slow-selling beer style. It simply won't be repitched frequently enough to maintain its viability. Sometimes your only recourse is to 'rouse' the yeast (basically, feed it a charge of sterile wort) to reinvigorate it. This is tedious and costly if it has to be done repeatedly, and if you are using malt extract for your wort charges, the flavor of the beer will be affected.

For this reason, it is generally better for a brewpub or microbrewery to settle on a single strain of yeast that, although it might not be optimal for every one of your regular beers, will be "user-friendly"; that is, it will settle well, be stable, resist mutation, pick up relatively little trub, and so on. Wyeast #1056 is an excellent all-purpose ale yeast, and although it may not be as estery as one would like for a nut brown ale, or as sulfury as one would like for an Alt, it is still capable of producing good results with both of those styles and many others.

Most brewmasters have a second reason for accepting the general principle that you should have only one yeast in a brewery: the threat of cross-contamination. If you are using three yeasts for different styles of beer, two of them represent a potential infection in every batch you brew. You have to be very careful with cleaning and sanitation, especially on the cold side of the process.

Because brewing is as much a science as it is an art, I figured I would try an experiment of leaving the trub in and taking it out on a couple batches. I did this several times, and the results were fairly consistent. The difference in the taste of the finished beer seemed small, but because no two batches ever come out the same it was hard to determine any difference resulting from trub removal. I did find that the fermentations were much faster with the trub left in the primary fermentor. The batches from which I removed the trub were much slower, taking up to 15 days to ferment; the batches with the trub left in usually took about four days.

The experiment continues: On my 13th batch I started partial mashing. It was a brown ale that included 3 lb pale ale malt, 1 lb crystal malt, 0.5 lb chocolate malt, 4 lb Alexander's extract, 0.75 lb dark brown sugar, 7 HBU Hallertauer boiling hops, and 1.5 oz Hallertauer finish hops. The mash produced only 50% extraction because of a coarse crush and less-than-perfect sparging techniques. The original gravity was 1.048. The yeast was a liquid British ale smack pack that I started two days earlier. After a 1-hour boil, and cooling to about 60 °F (16 °C), I put the wort through a nylon strainer to catch the hops but let the trub pass through into an 8-gallon plastic primary fermentor. I added the required water to obtain the desired gravity, pitched the yeast, and aerated the best I could by stirring.

I wanted it to be the best beer I ever made so I decided to remove the trub per your book. The next morning I racked off the clear beer from the 1/2 inch of trub. When the carboy was filled, I put the remaining beer from the plastic fermentor in a 1-gallon plastic milk jug to see what would happen. I put it all in, including all the trub. I figured this would surely prove the effect of trub in the beer during fermentation.

The trub beer fermented rapidly, mixing the brown trub into what looked like mud. I thought this stuff would taste terrible. After four to five days the trub settled out and left about 1 qt of clear beer on top. After a week the gravity was 1.010, so I bottled it (two 12-oz bottles). The main batch fermented slowly, as has been the case with my other trub-removed beers. I attributed this slow fermentation to an insufficient quantity of yeast and too cool fermentation temperatures (63 °F [17 °C]), though the temperature didn't slow down the trub beer.

One week later I tried the bottled trub beer. To my amazement, it was the best homebrew I ever tasted. It was similar to Brooklyn Brown and was as good as anything I've ever had from the hands of a professional. I couldn't wait to bottle the main batch because I figured that it would be even better.

Two weeks after brew day, the gravity of the main batch was 1.018. I was starting to worry. I added a packet of John Bull dry yeast, which changed the activity a little. Finally, four weeks after brew day, the bubbling stopped and the gravity was 1.013 so I bottled it.

Two weeks later I tried a beer from the main batch and it was a mediocre, typical home-brewed brown ale, much different than the trub beer. It remained unchanged even after two months. I was discouraged, but I realized that something must be missing in my main-batch beers and that if I could find out what it was, I could make beer that tasted great like the trub beer. All my beers made to this point were good but not like a good micro beer. This trub beer was the exception.

More brews with the trub left in: At that point I thought it would be best to leave the trub in during fermentation, which I did over the next five batches, three of which were partial mashes. For these batches, I made 24-32 oz starters for the liquid yeast and aerated like crazy. All of these beers fermented in four to five days. The beers were good but still not as good as the trub beer of batch #13.

More brews with the trub removed: I decided that if the pitching rate was high enough and the beer was aerated enough, I could leave out the trub during fermentation. Batch #19 would be the one. I bought a Corona grain mill, 7 lb Klages malt, some crystal malt, some Perle hops and a fresh smack pack of London ESB yeast. I started the smack pack six days ahead of brew day. Three days later I added that to 40 oz of water, 0.25 oz hops, and a cup of dried malt extract. The mash was low in yield because of my inexperience with the new mill, so I ended up with a gravity of 1.042 in 4.5 gallon of wort. After brewing, cooling to 69 °F (21 °C), straining out the hops, aerating, and pitching, I set the plastic fermentor in the basement overnight.

The next morning the beer had a 1-inch-thick krausen head. I racked into the carboy, leaving the trub behind. As in #13, I poured the trub and the little bit of beer into a 0.5-gallon glass container. Five days later the trub beer was very clear and done bubbling (S.G. 1.010), so I bottled it (two bottles). The same day, however, the main batch was 1.013. I added a teaspoon of yeast energizer and 2 tsp of yeast nutrient. It finished at 1.012 two weeks from brew day.

Again the flavor was drastically different between the trub beer and the main batch. The trub beer was very similar to Wild Goose Amber, while the main batch was good but lacked true greatness. I also can't figure the difference in specific gravity.

Batch #20 was an IPA partial mash in which I got 70% extract from my mash. The yeast came from the bottom of #19, and the beer fermented fully in five days with the trub (O.G. 1.062; F.G. 1.012). This beer is good, but still not great.

Batch #21 is a red ESB partial mash brew made without trub in the fermentor. Since I hadn't planned in advance for yeast culture, I used 15 grams (three packs) of Danstar Nottingham dry yeast that my homebrew shop owner recommended. I made 5.5 gallon so that I would have plenty of trub beer. I went through the usual procedures and racked the beer the next morning into the carboy, leaving the trub and 0.5-gallon of beer behind. The trub beer went into a 1-gallon milk jug and as usual looked like mud. It settled and cleared in four days (S.G. 1.010). I bottled it in six 12-oz bottles. The main batch, one week after brew day, had a specific gravity of 1.023. At nine days after brew day, I added 0.5 oz of dry hop pellets without a hop bag. This seemed to increase the fermentation rate. On day 12 the specific gravity was 1.013. I plan to bottle it on day 15.

I have recently read Papazian's newest book (3) and some articles about trub removal, including the ones on hot trub and cold trub in BrewingTechniques (4,5). It seems that when trub is removed, more oxygen is required; this may be why my fermentations without trub are so slow. In my next batch I am going to try to make a hop back to remove the hot trub, leaving the cold trub alone. This seems like the right approach, but it doesn't explain the trub beer's great taste and lower final gravity.

I know at least three other home brewers who on their first batches didn't aerate the wort at all, and they experienced no problems with fermentation. I have to believe that trub removal greatly affects fermentation, yet most literature doesn't mention it (except the articles in BrewingTechniques cited above). Maybe I'm used to four- to five-day fermentations and when it takes longer I think there must be a problem.

As you can see, this is not a one-time thing for me and I can't figure out what is going on. I would appreciate any help you can give me on the subject.

Why is the specific gravity lower with my trub beer, and why does it taste better when it should be worse? Why are the fermentation times drastically different? Am I missing something in my water? Does my water contain something it shouldn't? How do I make the whole batch taste like the trub beer? Has anyone else experienced the same thing? How much leaf hops do I need for a hop back to filter the hot break from 3.5 gallon of wort? Is there another test I can use to try to determine the problem?

Also, I checked with my local water authority and obtained a water analysis. It looks good from what I can tell, except for low levels of nitrates and nitrites. At what levels do I need to be concerned, and what do I do if the nitrates and nitrites levels are too high? Could this have anything to do with what is happening with the trub beer?

This trub beer experiment showed me that exceptional beer can be made at home. Unfortunately, I've only been able to make a few bottles so far. The bulk of my homebrew is good and I enjoy drinking it.

A: I am not entirely surprised by your results. One of the positive effects of trub in the wort is that it can serve as a substitute for oxygen, promoting yeast growth and therefore vigorous fermentation.

You are quite right that ale fermentations should go to completion in five or six days. Most of my batches here at Blackstone are finished in four or five. Longer fermentations generally mean high terminal gravities and more fermentation by-products. Trub also gives more fermentation by-products, especially fusel alcohols.

I think you are probably still not aerating your wort enough. Even with a starter (which, by the way, should be made up as soon as the yeast "smack pack" swells up) you will not put nearly as many yeast cells into a batch of wort as you would with 10-15 grams of dry yeast. The wort must be totally saturated with air to get sufficient yeast growth for a rapid, vigorous fermentation. Also, don't forget to aerate the starter as much as you can. (See the September/October 1995 issue of BrewingTechniques for an excellent discussion of wort aeration [6].)

The consensus of professional opinion on trub is that, other things being equal (and right) - including wort aeration and pitching rate - removing the hot trub will give a better tasting beer than leaving it in. With cold trub, things are not as clear. Most ale breweries make no attempt to remove cold trub, whereas most lager brewers feel that removing some of the cold trub (about half of it) makes for a cleaner-tasting beer (see, for example, the article on the Tabernash Brewing Company in the November/December 1995 issue of BrewingTechniques [7]). This disagreement may reflect differences between ale and lager yeast. Everyone, however, agrees that a problem fermentation - long lag period, slow fermentation, and incomplete attenuation - will generally result in substandard beer.

In your case, I think that the problem fermentations caused by underpitching and underaerating your wort definitely compromised the quality of your beer. The trub beer, which had a more normal fermentation, was better. But I think if you will make a yeast starter and thoroughly aerate your wort, you will be able to get a normal fermentation even though you separate the hot trub. Then you will get even better results.

Regarding your water, nitrate level is not important unless your water or wort has enterobacteria ("wort spoilers"), which can reduce the nitrate to nitrite. As far as nitrites are concerned, most city water supplies have levels under 1 ppm. Unless your water supply contains more than that amount, it is probably not a factor in your fermentations.

With all-grain beers, yeast nutrients should be unnecessary. In the bad old days before I put together a wort aerator, I sometimes tried nutrients to get the beer off to a faster start. It didn't work, and some of the preparations left a bitter, unpleasant flavor in the finished beer.

The hop back is a traditional way to filter out hot trub. It is difficult to implement on a homebrew scale because the pipe that carries the hot, hop-filled wort from the kettle to the hop back has to be big enough to allow the whole hops through without plugging it. Another problem with hop backs is that they tend to cause aeration of the hot wort.

In any case, what you probably have in mind is using pellets for your boil hops and putting whole finish hops in the hop back before running the wort into it. I have never worked with a hop back, and I would welcome advice and comments from readers about the feasibility of such a device for home brewing.

Most microbrewers, and an increasing number of home brewers, whirlpool the wort in the kettle and then allow the trub and hop pile to settle before drawing out the clear wort. This is easy to do using pelletized hops. If you want to use whole hops, I suggest putting a piece of screening or a slotted copper manifold on your kettle draw-off (whether it is a metal racking tube or a tap) to keep the hop petals from plugging it. This is simpler than making a dedicated hop back.

Two pieces of advice: First, let the whole hops settle to the bottom before you start drawing off wort. Second, draw the wort off slowly. Even a screen with a fair amount of surface area can get plugged if you get impatient.

References

(2) Dave Miller, The Complete Handbook of Home Brewing (Storey Communications, Inc., Pownal, Vermont, 1988).

(3) Charlie Papazian, The Home Brewer's Companion (Avon Books, New York, 1994).

(4) Ron Barchet, "Hot Trub: Formation and Removal," BrewingTechniques 1 (4), pp. 38-41 (July/August 1993).

(5) Ron Barchet, "Cold Trub: Implications for Finished Beer, and Methods of Removal," BrewingTechniques 2 (2), pp. 32-35 (March/April 1994).

(6) Don Put, "Give 'Em Some Air! Early-Stage Aeration Is the Key to Robust Fermentations," BrewingTechniques 3 (5), pp. 18-24 (September/October 1995).

(7) Norm Pyle, "Tabernash Brewing Company - A Colorado Microbrewery Gets Serious with Traditional German Lager," BrewingTechniques 3 (6), pp. 70-78 (November/December 1995).