Q-&-A with the Troubleshooter
Dave Miller takes on...
  • Room-Temperature Filtration and Carbonation
  • Brass Valves
  • Fermenting Ale Yeast Cool
  • Brewing Water
  • Remedies for a Moldy Refrigerator

    Republished from BrewingTechniques' September 1997.

    Room-Temperature Filtration and Carbonation

    Q: Thank you for addressing filtration/clarification in two chapters of your home brewing guide (1). I have looked at several books and magazines as well as The Brewery website (, and none addressed the topic of filtration sufficiently. Although I do prefer unfiltered beer, my fiance is becoming intolerant of my gaseous condition after I consume homebrew naturally carbonated with yeast. I have set up a three-stage cartridge filter system. I also happen to lack a temperature-controlled chest freezer with which to refrigerate my soda kegs, which makes cold filtration and cold force-carbonation impossible. Do you have any experience with or have you heard of success with force-carbonating room temperature, filtered beer? If so, do you know how long it takes to achieve adequate carbonation under these higher-pressure, room-temperature conditions?

    A: Even though you have no freezer in which to chill all your soda kegs, you probably have some way of chilling one or two of them. I strongly recommend chilling beer (down to 32° F [0° C] if possible) for at least three days before filtering.

    Chilling your beer offers two benefits. First, most brewer's yeasts will flocculate and drop to the bottom of the keg if chilled, easing the demands you are asking of your filter. Most homebrew filters have only a limited capacity and can be "blinded" (plugged up with yeast cells) very quickly. When this happens, your only recourse is to backflush the filter with water, which is tedious and usually results in some beer loss. Anything you can do to lessen the burden on your filter is worthwhile. Chilling the beer is one of the best things you can do. Fining will also help.

    Second, chilling the beer before filtration will result in a clearer beer. Beer filtered at room temperature will still throw a chill haze when you cool it down for serving. The haze particles must be formed before they can be trapped by the filter.

    My best recommendation is to filter the beer cold if you possibly can. If you really can't chill the beer in a refrigerator, at least give it a dose of finings (to help yeast drop out) and add a clarifying agent such as Polyclar or silica gel (to remove chill haze precursors) and let the beer settle for a few days in a cool spot before filtering.

    As for carbonation, I cannot recommend trying to carbonate warm beer. At least cool it down to 50° F (10° C). I have successfully carbonated homebrews at that temperature. Carbonating at this temperature still takes more time and pressure (which may be a problem if your hoses are not in good shape), but you should be able to get your beer force-carbonated in an hour or so with intermittent shaking.

    Brass Valves

    Q: I am fabricating a brew kettle from a 15.5-gallon stainless steel keg with the top cut off and a 3/4-in. stainless threaded nipple welded near the bottom. As the setup is described in your book, I need a valve on the nipple for draining the wort. I would like to put a stainless ball-type valve there, but industrial supply companies charge about $80 for them. I have seen no copper-bodied valves that will fit on a 3/4-in. pipe thread, but my local hardware store has brass-bodied ones for $10. You discuss copper and stainless steel as brew kettle materials, but what about brass? I've never seen brass fittings used in cooking, and I assume there is a reason. What are the risks and reasons, or can I use this brass valve?

    A: Professional brewers prefer stainless because it is very tough and will stand up to corrosive cleaning chemicals. Brass is softer and can be corroded. Another problem with brass is that most brass contains a small amount of lead. Fortunately, the lead can be removed by treating the brass with acetic acid and hydrogen peroxide (for more details, see reference 2). I agree, consumer prices for stainless valves are out of sight (so are the prices microbrewers pay!). Brass should work alright as long as you "de-lead" it before use and avoid caustic-based cleaners or oxidizing acids such as nitric. Stick to noncaustic products and the brass should hold up well. (For sources of noncaustic cleaners, consult the listings in The 1997 Brewers' Market Guide [3] and advertisements in BrewingTechniques.)

    Fermenting Ale Yeast Cool

    Q: I need some help with temperature-dependent fermentations. I recently read that some of the neutral American ale strains, such as Wyeast #1056 (American Ale; Wyeast Labs, Hood River, Oregon), ferment trisaccharides at warmer temperatures but cannot ferment them at cooler temperatures. Furthermore, some other yeast distributors such as Kent Labs (Ann Arbor, Michigan) and Brewtek (Brewers Resource, Woodland Hills, California) claim that their neutral American strains will produce softer, fruitier aromatic ales when fermented cool. Are they alluding to temperature-dependent fermentation of trisaccharides? Why wouldn't these strains be able to ferment trissaccharides at lower temperatures? Would cooler fermentation stress the yeast and make the wort more susceptible to contamination? If I were to try this, would I have to increase my pitching rate? How long would you expect my primary fermentation to last?

    A: I have worked with only a small number of yeast strains. Wyeast Labs #1056 (once dubbed "Chico Ale " and now renamed "American Ale") happens to be the one I have used most. In my experience, this yeast is a tenacious fermenter. I typically mash high with a single infusion at 152-156° F (67-69° C). Even with worts made in this way, Wyeast #1056 usually gives about 75- 80% apparent attenuation. This holds true whether I run the fermentation at 65, 70, or 75° F (16, 21, or 24° C).

    My other observation is that the beer's flavor and aroma seem to be scarcely affected by temperature. In fact, I generally advise home brewers to select another yeast strain for making big, fruity beers such as barleywines. Even though Wyeast #1056 is an excellent attenuator with good alcohol tolerance, it simply will not produce the fruity-solvent "punch in the nose" that is part of such beers' flavor profiles. The last time I made a barleywine, I tried a warm fermentation (75° F [24° C]) to see if I could get more esters. Alas, no difference.

    The one thing I and at least one other microbrewery have encountered occasionally with Wyeast #1056 is perceptible diacetyl formation during low-temperature fermentations. I recently discussed this with Dave Logsdon of Wyeast Labs. We both believe it may be due to a buildup of respiratory-deficient (RD) mutants in the yeast caused by repeated repitching, but this is just a hypothesis. Logsdon has never encountered a diacetyl problem with Wyeast #1056, though he has noticed that RDs can build up in it. The yeast is so hardy that it encourages repeated use. In any case, as long as I stick with a fermentation temperature of 70° F (21° C) the beer is clean and I can go a year before getting a fresh culture.

    Based on my experience, I would suggest that you stick with pitching and fermenting at 70° F (21° C). If you want to try 65° F (18° C), however, a normal pitching rate should still suffice. The lag period may be a little longer but, in my experience, should still be less than 12 hours.

    As for other American-type ale yeast strains, having never worked with them I cannot say whether a lower fermentation temperature would make them attenuate any less. I do know, however, that you can reduce or even arrest attenuation with many yeast strains by manipulating fermentation temperature. Response to temperature is strain-specific; with some yeast strains, a difference of 5 degrees up or down can make a very different beer. So the claim seems plausible. Keep in mind that ale yeasts are a bit easier to trick than lager yeasts, which are more tolerant of cold temperatures.

    Also, higher fermentation temperatures generally result in more esters (fruity aromatics) and other by-products. I do not equate "fruitier" with "less attenuated," so I am puzzled by the claim that a lower fermentation temperature would yield a fruitier beer. "Softer" seems more plausible because a less attenuated beer will have more residual carbohydrates and a fuller mouthfeel. If any of the microbiologists who market these yeasts would care to comment, I would welcome more details about their yeasts' performance.

    I would not worry about contamination as long as you pitch a sufficient amount of yeast and aerate the wort thoroughly to get good growth in the fermentor. The lag period will be longer at lower temperatures, but remember -- cold slows everything down, bacteria as well as yeast. Just be sure you don't shock your starter yeast by pitching into a wort that is much cooler than the environment in which the yeast were grown. A drop of 18° F (10° C) is generally considered the allowable maximum.

    Brewing Water

    Q: I recently learned that my water contains very little calcium and magnesium (5.6 and 1.9 ppm, respectively). In brewing pale ales and India pale ales, would you recommend adding epsom salts as well as gypsum? Is additional magnesium needed for healthy fermentations, even if I use yeast nutrient in my step cultures (which I prepare in 500- and 2,000-mL flasks)?

    I also filter my water through a carbon-type drinking water filter to remove chlorine. I can always smell chlorine when I fill the bathtub, even though my water report claims the water contains only 1.02 ppm free chlorine and 1.20 ppm total chlorine. Am I just wasting my time by filtering? Could I also be removing essential magnesium and/or calcium? I look forward to any light you may shed on these topics.

    A: You do not need to add epsom salts to water for yeast nutrition. Malt contains plenty of magnesium for the yeast. My general recommendation on water is to add calcium salts only as needed to adjust mash pH (use calcium chloride or sulfate to lower pH; use calcium carbonate to raise it). Get your pH values right to start with; then, in subsequent batches, experiment with water treatments and their influence on flavor if you wish. My personal experience suggests that trying to duplicate the brewing liquors of historic sites such as Burton is seldom worth the effort. Even when it can be done, it will not enable you to duplicate the beer.

    You are not wasting your time with carbon filtration. Carbon filters remove chlorine and organics, including trihalomethanes. They have no effect on metallic ions -- whether good ones like calcium, or bad ones like iron. As far as chlorine goes, 1 ppm is a lot -- enough to keep your drinking water pure, and also enough to leave medicinal flavors in your beer. Your nose is telling you the truth. The rule on chlorine is, if you can smell it, you need to get rid of it before you use the water for brewing. The same, of course, is true for other off- flavors and odors.

    Remedies for a Moldy Refrigerator

    Q: I recently modified our old freezer for draft beers by installing a custom-built temperature controller. It keeps the beer (ale) at about 49° F (9° C), and the size is ideal for four soda kegs. One problem I hadn't anticipated is mold. You can smell and see mold everywhere, including at the open ends of my cobra (picnic) taps, which I try to shake as dry as possible after filling my glass with beer. All lines and taps are kept inside the freezer.

    I talked to a refrigeration technician, and he said that freezers weren't designed to run so warm. He suggested I may get less mold if I run it well below 40° F (4° C). Apparently, refrigerators run at much lower humidity levels and hence have no mold problems.

    What is your experience in this area, and what solutions would you advise?

    A: Your technician is basically correct about humidity being an underlying cause; however, my experience with a walk-in cooler at the Tap Room in St. Louis, Missouri (which was held at 38° F [3° C]) suggests that lower temperatures may not help that much. We had mold in the corners, on the beer lines, pretty much all over. Mold is one of the best adapted organisms on the planet. All it needs is water, oxygen, and some sort of nutrient; apparently almost anything, including rubber or plastic hoses, can serve as a nutrient.

    My first suggestion is that if your freezer does not already have a drain, go ahead and drill a drain hole in the bottom of it. Be careful not to drill anywhere near the refrigerant lines or cooling plates. A drain will at least prevent water from pooling on the floor of the chest.

    The next step is to institute a thorough cleaning program. Remove all the kegs, lines, and everything else from your freezer and disassemble all the hoses (that is, remove clamps, cobra heads, hose barbs, and so forth). Soak all the small parts in a bucket of warm PBW (Five Star Products and Services, Commerce City, Colorado; see reference 4 for for PBW distributors) or other noncaustic cleaner (see reference 3 for suppliers) and scrub them individually with a toothbrush or whatever tool it takes to get the mold off. Small, round cleaning brushes will let you get inside the cobra heads and hose barbs. Make them look like new. If possible, replace all the hoses; if that is too expensive, at least soak them in PBW and wash the outside surfaces with a sponge.

    Next, attack the freezer. Get it out in the driveway or somewhere you can hose out the interior. When you have hosed out as much mold as you can, wash the interior with a PBW solution and a sponge. Then rinse out the interior thoroughly and -- this is vital -- let it air-dry before returning it to service. Air-dry all the small parts as well, or soak them in a sanitizer solution until you reassemble them.

    To prevent a recurrence, spray the inside of the freezer and all the lines, kegs, and so forth every week with an antifungal agent. Quaternary ammonium compounds (or quats) work well for this; Quantum (also from Five Star) is one such product, but all manufacturers of cleaning supplies sell quats. Quat is a better choice for this duty than chlorine bleach because it is not as corrosive to metal and it has residual killing power (chlorine dissipates in a few hours). The only problem with quats is that they break down beer foam. So when you spray the quat, don't hit the cobra heads.

    Even with preemptive spraying, you may find that you have to clean your freezer and beer line fittings once or twice a year. As I said, mold is persistent.

    One final suggestion: Because your primary goal is to prevent moldy flavors from entering your beer, it will probably be worthwhile to keep your cobra heads soaking in a small container of sanitizer inside the freezer. Unactivated chlorine dioxide at 200 ppm would be good for this (10 mL/L).


    (1) Dave Miller, Dave Miller's Homebrewing Guide: Everything You Need to Know to Make Great Tasting Beer (Storey Publishing, Pownal, Vermont, 1995).

    (2) John Palmer, "Brazing and Welding 304L Stainless Steel," BrewingTechniques 2 (6), pp. 50-55, (November/December 1994).

    (3) The 1997 Brewers' Market Guide (New Wine Press, Eugene, Oregon, 1997).

    (4) Greg Foss, "The Dirt on Brewery Cleaning -- A Review of Procedures and Chemicals," BrewingTechniques 5 (2), p. 74 (March/April 1997).

  • Issue 5.4 Table Of Contents
    [Home]  [BrewingTechniques Library]  [Contact Us]  [Order]