Is it detrimental to store wort before boiling it? I plan to take the liquor from the abovementioned mash tun and store it at 32 °F or so until it can be used. I will run it through my heat exchanger to cool the liquid quickly and then carefully run it into sanitized plastic drums for storage (attempting to prevent oxidation in the process). The time between storage and use should be less than a couple of days. Will the chilling of the wort before boiling cause a premature cold break? If so is that a bad thing?

DM: A 400-gal tank is a big vessel - almost 13-bbl capacity, which is enough for a mash/lauter tun for a 10-bbl microbrewery. How much wort are you planning to make? Remember that you will have to use enough grain to get a bed depth of at least 5 in. For this size of vessel, I estimate that your minimum grist would be around 400 lb, enough for 250-300 gal of average-strength wort. This assumes that the proportions of your proposed mash/lauter tun are pretty normal; most mash/lauter tuns in microbreweries are between 3 and 4 ft deep. If your vessel is very tall and narrow, it may allow you to do smaller mashes.

The question about dimensions raises another issue. The converted dairy tank lauter tuns that I have seen were insulated. This insulation provides an important benefit in maintaining temperature during the conversion stand. The tanks I have seen, however, had no manway on the side, and the insulation makes it difficult and expensive to install one. Without a side manway, you will have to lift every shovelful of wet spent grains up over the side of the lauter tun and into a trash can or other container. The higher the sides, the higher the lift. The wet spent grains will weigh at least 11/2 times as much as the dry grist. Think about whether you are up to the task of shoveling out that grain regularly.

A manifold of copper or stainless tubing is a viable alternative to a screen bottom for a mash/lauter tun. Anheuser-Busch developed such a system for lautering many years ago called the Strainmaster, and they may still be using these vessels in some of their breweries.

Here are some suggestions in case you decide to use this arrangement for your vessel: Cut slots in the tubing rather than drill holes. Slots are much harder to plug up, giving you a better chance of getting a smooth, uniform runoff. Cut the slots in the lower side of the tubing. Use a thin hacksaw blade and space the slots about 1 in. apart. Also, be sure you get enough drainage. Space the manifold tubes every 6 in., and use 1-in. i.d. tubing.

Give some thought to how you are going to clean the vessel. Even if you are willing to shovel grain up and over the side, you won't be able to tip the thing on its side to drain out the wash water. Install a drain fitted with a valve on one side or, if the bottom is dished, in the center. Also, you will have to wash the grain husks out of the collection manifold after each use, so you will need to have a large supply of water available for backflushing. I recommend a 1-in i.d. supply line and 1-in. i.d. hose.

Your second question is more difficult. I have never tried the process you describe, so I cannot say how it would affect the flavor of the finished beer. I speculate that the break might be affected - probably less break would form in the kettle because of precipitation of material during the cooling - but what effect that would have on the final product I cannot say.

Another potential problem is microbiological stability. Before boiling, wort is far from sterile. In particular, it contains thermophilic (heat-loving) strains of lactobacilli, which are responsible for the souring effect in sour mash brewing. How much they would sour a refrigerated wort I do not know. In any case, to minimize their activity you should chill the wort to near freezing as quickly as possible. I suggest you try an experiment by making some 5-gal homebrew batches according to the method you propose, and see what happens. A split-batch trial, where you refrigerate half the wort before boiling and handle the other half in the normal fashion, would give the most useful information. Remember to change only this one variable; use the same yeast, fermentation temperature, and so forth.

One practical caution: Unboiled wort contains a lot more colloidal material than does boiled wort, so the soil buildup in your heat exchanger (wort cooler) will be greater. You will therefore have to be especially diligent in cleaning and sanitizing it. For the size batches you are contemplating, a closed counterflow system is the only practical design. Backflush it with caustic soda after every run, and leave it full of sanitizer between uses.

One final suggestion: I have no idea what your level of experience is. The project you are proposing is of a significant scale and involves the kind of practical problems associated with building a microbrewery. If you lack experience in this area, enlist the help of someone who has it. Without looking at your vessel and the place you intend to install it, there is no way to anticipate all the problems you may encounter in putting your idea into operation.

DM: As I understand it, the RIMS design does not clarify wort. It pumps the whole mash - grain and all - around and around through a tube that contains a heating element, which cycles on and off to maintain the mash temperature. The common rap against the RIMS is that excessive agitation causes increased extraction of husk tannins, resulting in an astringent, grainy taste in the final beer. Some early prototypes of the design did apparently suffer from such a problem, but more recent versions appear to have solved it. I do not know of any reports of adverse effects on fermentation. Conventional brewing wisdom holds that agitation of infusion mashes should be kept to a minimum. Occasional stirring, however, and cutting the grain bed during sparging, do not seem to produce a noticeable tannic flavor.

My own view of the RIMS approach is that it seems to be a solution in search of a problem. The system's claimed advantage is precise temperature control, ±0.1 °F of the target temperature, combined with excellent uniformity of temperature throughout the mash. This is impressive but, fortunately for microbrewers, not really necessary. A microbrewery is doing well to keep its mashes within ±1 °F of the target temperature. This is not enough variation to produce an obvious batch-to-batch discrepancy in the finished beers, if everything else is held as constant as may be.

DM: The most critical stage for measuring pH is the mash, especially during starch conversion. The malt enzymes a- and b-amylase require a slightly acid pH to do their work. Values in the 5.0-5.7 range are alright, although values toward the lower end (5.1-5.3) are usually considered optimum. It is important to measure pH at room temperature; a phenomenon called displacement will cause pH to read lower at mash temperatures than at room temperature. Cool the mash liquid sample before reading or, better, get an instrument with automatic temperature compensation (ATC) built in.

The pH of wort in the kettle is also important for a good break reaction and is worth checking. The best range is the same as that for the mash. Wort pH and mash pH are usually similar, but if your sparge water is alkaline the wort pH may be higher. To correct this difference, you can adjust the pH of the sparge water or the wort with acid. I prefer phosphoric acid for pH adjustments. It is safer than other mineral acids (such as hydrochloric) and more stable than organic acids (such as lactic acid).

The pH of fermenting beer drops very rapidly once fermentation begins, usually getting close to its final value after 24 h. In general, ales have a slightly lower pH than lagers; typical values for ale are 4.0-4.5, for lager 4.4-4.7. Each yeast strain, however, has its own characteristics. If you usually work with only a few strains of yeast, you may want to check the pH of your fermented beers to get an idea of what your yeast is giving you. If the pH goes up or down over successive batches, it may be a symptom of contamination and a signal to go to a fresh yeast culture. This can be especially valuable because you may not notice a gradual change in your beer, especially if it is slow and not terribly obnoxious in character.

By the way, carbon dioxide has a great effect on the measured pH of fermented beer. Always degas the sample before measuring. The easiest way to degas beer is with a blender.

The pH of the fermented beer changes very little during lagering or conditioning. It may be worthwhile to check it before bottling if you suspect a slow-working infection (that is, one that asserts itself only after the fermentation is over). Your nose and taste buds, however, will usually give you the answer just as reliably as a pH meter.

DM: Record each beer recipe and all measurements associated with the brew, such as the volume and strike temperature of the mash water, mash temperatures at the various times and stages, total time for each step in the process, and so forth. The numbers will give you a way to compare your procedures so that you can explain differences in your results.

It is impossible to give a complete list because brewing processes are so variable. At minimum, however, it is a good idea to record the recipe (amounts and specific types of ingredients and how they were used) and basic fermentation data, including original and terminal gravity and temperature. If you have a fairly elaborate process, your log sheets should reflect its complexity. At the Saint Louis Brewing Company we use a six-page form to record data for each brew. On the other hand, a simple malt extract brew might require only a page or two to record all the relevant information.

A number of predesigned, preprinted log forms have been published over the years. I suggest that you at least look at some of these or at the logs kept by other brewers you know to get an idea of what information you might want to record. It is easy to overlook things if you are just writing notes on a blank sheet of paper. On the other hand, it is highly unlikely that someone else's form is going to fit your methodology and your preferences exactly. Over time, you will probably find yourself adding notes in the margin. When this happens, it may be time to have a go at designing your own form. A good word processor and printer make this easy, and you can change the form as often as you wish.

I would not try to make my log entries directly into a computer. Log records are made on the fly, so to speak, in various parts of the house and often in places where a computer, even a portable one, does not belong, like a steamy kitchen with a kettle of wort boiling away. A paper form attached to a clipboard and a ballpoint pen are much more rugged and cheaper to replace if wort or beer is splashed on them. This is not a criticism of the various computer programs that have been published specifically for home brewers. Many of them provide valuable help with number crunching and other aspects of brewing. I do not believe, however, that they can take the place of a good paper log form that is customized to your brewing method and that can be carried around with you.

Whatever form you decide to use, do not limit yourself to recording numbers. Verbal descriptions of various activities - especially accidents or unusual occurrences - are just as important. The more notes you write to yourself about your brewing, the more you will learn from each brew session. Reviewing these notes periodically will help you formulate hypotheses about why you encountered certain difficulties and may suggest possible courses of action to solve them. By taking careful notes about our sparging operations, for example, I have learned that, at least with our mash/lauter tun, a thin mash makes it easier to clarify the wort and keep it clear during runoff and sparging.

Records are the key to learning from your brews. The more time you put into your log, the better it will serve you.