Jeff Flowers on June 5, 2015 11 Comments Photo Credit: Grongar / Flickr I am often presented with the debate of plastic verses glass carboy and which one is better to use during the brewing process. I’ve had plenty of experience using both of these for primary and secondary purposes. Here’s some insight in what you should consider when buying or choosing between the two types of carboys. What is a Plastic / PET Carboy? First off, PET stands for polyethylene terephthalate (PDF), a type of polyester resin that has been widely tested to meet or exceed FDA food contact requirements. It is not uncommon to come across food and cosmetic products packaged in PET containers. In fact, you probably have some of these in your home right now. To find out, turn over any plastic containers and look for the recycling symbol with a number in the middle. If that number is 1, then that’s a PET product. For brewing purposes, PET vessels are commonly used for primary and secondary fermentation. They come in many sizes, the most common being 3, 5 and 6 gallon carboys. I personally have one of each size, as I like to use these for experimental batches. The 5 gallon PET carboy is the one I mainly use for secondary fermentation, whereas the 6 gallon is used for primary beer fermentation, or secondary wine fermentation. The Advantages of PET Carboys: Let’s take a quick look at some of the main advantages that PET carboys have over glass carboys. You may find other advantages that aren’t listed here, and if you do, please discuss them in the comments below. 1. Light-Weight The first thing you’ll notice when taking your PET carboy home is how light it is. Compared to glass, it feels as though you can throw your PET vessel about 100 yards. This is easily one of the biggest advantages they have over glass carboys. The weight of a full 6 gallon glass carboy is not only cumbersome, but potentially dangerous. Ask any experienced homebrewer and they’ll confirm, carrying a full glass carboy always seems like a gamble. One wrong move, one slight bump into anything that vicariously wonders into my path of me and it could be disastrous. Not only would this spell catastrophe for my carboy, but also the precious cargo inside, as well as anything within a 10 foot radius. This is especially dangerous for people, as a glass carboy will send shards of glass everywhere, likely landing you in the emergency room for stitches. While this may seem extreme, it does happen. On the other hand, the light-weight material of a PET carboy is extremely durable. While carrying it, I can bump into things and not have to worry about breaking anything or losing the contents of what is inside. Most importantly, I don’t have to worry about glass shards shredding up my shins. 2. Larger Neck & Opening Another thing that I enjoy about PET carboys is that many of them have a larger neck and opening, sometimes referred to as a mouth. Not only does this larger opening make it easier for you to clean the equipment when you’re finished using it, but it also allows better access for pulling out secondary additions. For example, let’s say you put 1 ounce of dry hops in a muslin in your glass carboy. When it comes time to pull them out, this can sometimes be a challenge. And a dangerous one at that. This is because the hops absorb your beer, thus expanding and making it difficult to pull the muslin bag through the smaller opening of the glass carboy. However, with the larger opening of a PET carboy, you are less likely to experience this problem. In fact, from my experience, pulling out a muslin bag with one ounce of dry hops is never a problem. Pulling out two ounces is a bit more difficult, but still comes out relatively easily. One downside of this larger mouth, is that you will need to buy a larger stopper/bung than what fits a glass carboy. Likely, you will need a #10 stopper, but this may sometimes vary from brand to brand. 3. Install a Spigot Another advantage that a PET carboy has over glass, is that you can easily install a spigot, or buy one with a spigot already built-in. Technically, you can install a spigot on a glass carboy, but it’s not recommended for a wide variety of reasons. If you want a carboy with a spigot, we’d recommend buying one with a pre-drilled hole or a spigot already built-in. But that’s not always convenient, especially when you already own the equipment and just want to convert it on your own. Instead of going into the process of how to do this, I’ll let you find some instructions online, as I have never done this and don’t want to steer you in the wrong direction. It must also be noted here, that having a spigot in your carboy is not necessary. And it will also be difficult to cleanse and sanitize. It’s definitely a nice feature to have, but you should weigh the pros and cons before you buy or install one yourself. 4. Easier to Clean Cleaning a PET carboy is simple. I use the same cleaning practices that I use on my glass carboys. I have a Jet Bottle Washer that I use to spray away any yeast, hop, or protein trub that has accumulated in the bottom of the carboy. Then fill the carboy with an alkaline cleaner. I prefer to use PBW to clean all my brewing equipment, but there are many cleansers available. I’d recommend using one of the following methods: Carboy Cleaning Tablets: One popular option for cleaning carboys, is to use these cleaning tabs. Simply fill the carboy with hot water and drop in the tablets. This helps loosen and remove soils and other buildup, making it easier for you to clean the hard-to-reach places. Alkaline Brewery Wash: Another popular cleaning method, is to fill your carboy with hot water and add in a few tablespoons of an alkaline brewery wash, sometimes referred too as powdered brewery wash (PBW). Then simply let it soak over-night. This will help loosen and remove the debris, allowing you to easily rinse out the carboy the next day. Elbow Grease: The unpopular, yet original, method is good ole hard work and lots scrubbing. This method works by using water and a carboy brush to scrub down the inside of your carboy. It may not be popular, but it works. All of these cleansing methods work for PET and glass carboys. The reason why PET vessels are easier to clean, is because they not only weigh less when filled with water, but they’re also easier to drain. When draining, it’s not uncommon for water to splash around and, eventually, land on you and the carboy itself. If it’s glass, this may cause your carboy to become slippery, increasing the risk of you dropping it. That same risk still applies for PET carboys, however, the difference being that you won’t have shards of glass everywhere if you drop it. Not to mention that PET carboys are somewhat textured, giving you a better grip. Common Myth About Plastic Carboys Something that most people mistake with PET carboys is that they assume since they are plastic that they allow oxygen into your beer. The amount of oxygen that creeps in is almost negligible. If a glass carboy has a rating of 100 out of 100 for protecting against oxygen, I would easily give a PET a 99.9 out of 100. Sure, they may let in some amounts of oxygen, and we all know that oxygen is bad for your beer. But in all my years of brewing with PET carboys, I’ve never noticed a hint of oxidation. Obviously, this is just one brewers account, and others may spin a different tale. Fair enough. But in the end, I’d be willing to bet that the erroneous ways of the brewer are often to blame for a bad beer, than a minute hint of oxygen that a PET carboy may or may not let in. Too Long; Didn’t Read The overall light-weight nature and ease of cleaning is what sets PET carboys apart. There are a couple other options and features available that would be difficult to replicate with a glass carboy. Are those features necessary? Perhaps not, but they sure are nice to have available. At the end of the day, whether you use glass, PET or a fermenting bucket, it’s all about brewing great beer. You may prefer the feel of glass, and there’s nothing wrong with that. But, there’s no denying the potential drawbacks of glass carboys.