Dear Mr. Wizard:

Would you recommend using water with ozone in it to sanitize brewing equipment rather than chlorine? I found a local dealer who sells an "under the sink" ozone machine that connects in-line to your existing water line. He said that the ozone would not affect the stainless steel and would dissipate after a short period of time so as not to leave a residue. Also, what do you think about passing finished beer or wine through the ozone machine and using it as a yeast filter? It seems as though the ozone would kill the ambient yeast still in the finished beer, as well as any foreign bacteria that might still be present when it's time to keg or bottle the batch.

K. Hewitt
Salina, Kansas

Mr. Wizard replies:

When ozone is bubbled through water, the water is said to be "ozonated." Ozone is a potent oxidizing compound due to its instability and it breaks down according to the following chemistry: O3 -> O2 + O· The O2 of this equation is the most common form of oxygen in the atmosphere but the O· is special and is known as free radical oxygen. Free radicals are very reactive chemical species and, among a long list of attributes, lethal to microorganisms. The lethality of free radical oxygen makes ozonation an effective method of sterilizing water, commonly used for bottled water. The free radical oxygen eventually combines with other free radical atoms to become garden-variety O2, so ozonation leaves no residual.

Ozonated water is not used in breweries as a sanitizer, although some breweries do use ozonated water to rinse bottles prior to filling. Ozonated water may work as a sanitizer for equipment, but to my knowledge this would be a new application. I would recommend using a conventional sanitizer unless you wish to pursue your idea on an experimental basis.

Coming up with new technology is exciting, but your second idea would ruin your beer. For starters, ozonation would oxidize beer to the most extreme end of the oxidation spectrum. Also, free radical oxygen initiates rancidity, the breakdown of fats and oils into fatty acids. Use ozonated water in any brewing step requiring water, if you want - there will be no harm done in mashing, and if you dilute your wort after cooling it may add a little bit of oxygen prior to fermentation. However, resist the temptation of running beer through an ozonator. Not only will this ruin your beer, it may damage the device!

Dear Mr. Wizard:

I brewed a batch of lager (a three-gallon batch in a five-gallon carboy) and instead of the normal CO2 venting out of the air lock, a vacuum formed. I used a wort chiller and pitched the yeast at 72° F. At 18 hours the cap was sucked down onto the vent tube with liquid (vodka) suspended in the vent tube (wort temperature 64° F sitting in my basement). I moved the carboy to a refrigerator sitting in a cold garage and the wort temperature dropped to 54° F over the next 18 hours. The same vacuum was present at 36 hours. Finally after 48 hours a slow fermentation was going with the cap raising, but it was three-plus days before a strong fermentation was present. Could the rapid temperature change or poor yeast start have caused the vacuum? What happened and what can I do to prevent this in the future?

Larry Silbernagel
via e-mail

Mr. Wizard replies:

What happened to your fermenter was due to the relation between gas temperature, volume and pressure. A sealed container will exhibit a decrease in gas pressure if the container is cooled and conversely its pressure will increase when heated. Fermentation airlocks allow gas to escape and a cool carboy that is heated will not build pressure. However, a warm carboy that is cooled will exhibit a drop in pressure. This vacuum will suck liquid from the airlock into the carboy. Eventually the airlock will be empty and the vacuum will be relieved. If your fermentation took off more quickly and/or your wort was cooled to the same temperature as your basement this would not have occurred. This phenomenon is easy to avoid early in the process, but if you cool your airlocked carboy after the primary fermentation is complete, the vacuum will return. I prevent any liquid from an airlock being sucked into my beer by removing the airlock and covering the carboy with aluminum foil. After cooling, I replace the airlock.

Vacuum is not a major problem for homebrewers, but it is perhaps the most devastating force present in large tanks. Big tanks are designed to withstand some sort of pressure, but are rarely designed to cope with vacuum. Big tanks can be sucked in like a tin can if they are not treated properly, for example rinsing a large tank with cool water after a hot wash. If you keep in mind that a vacuum is created when you go from hot to cold you will easily prevent this problem.

Mr. Wizard, BYO's resident expert, is a leading authority in homebrewing whose identity, like the identity of all superheroes, must be kept confidential. To see more of Mr. Wizard, check out the latest issue of Brew Your Own at better homebrew shops and newsstand locations.