advanced seltzer engineering
Over the past few years, many of you have heard me evangelize the gospel of home carbonation. At work we’ve recently taken things to a new level, and I’ve had a couple of people ask me questions about it. As you can imagine, I’m delighted to answer them. But let’s begin at the beginning.
My interest is in making seltzer water — growing up we called it “bubbly water”, and my dad bought it by the case. I’m not sure why I like it so much: the slightly acid tang of the carbonic acid in solution? The cooling, quenching sensation I feel as the dissolved gas pushes the water out of my stomach, into my intestine and on to my bloodstream? I’m not sure. But I really like it.
Until recently, soda siphons were the only way to make seltzer at home. But the pricing doesn’t work: the tiny CO2 cannisters that power the things, while handy — my dad once told me that in his youth he used to stuff empties full of matchheads to create what must have been an awesomely dangerous projectile — are so expensive that you’re much better off lugging liter bottles home from the store.
My then-neighbor Rob Goodspeed was the first person I knew to have a Soda Club. It was during the golden age of PR flacks sending bloggers things for no apparent reason, and Rob had cofounded DCist, earning him rights to substantial swag. Most of these pitches were laughably inept either because the product was awful or the pitch was tone-deaf (as a technology blogger, of course I was the right person to email about custom popcorn flavoring powders). It didn’t feel like much of an ethical conundrum — it was all too stupid for that. But occasionally the flacks would succeed, and the original Soda Club was such a case. Rob was justifiably enthusiastic about the product, and as soon as I saw it I decided to buy one for myself. I’ve gone on to buy units for friends and parents and siblings, and I’ve talked many more people into doing the same. It’s a great product.
The company has since rebranded to SodaStream (I like to think our Club is no longer accepting new members), and is even publicly traded (as $SODA, of course). My original Soda Club carbonator is still going strong.
its operation is simple. You fill a bottle with a liter of cold water and screw it into the unit. You depress a button several times, until the overflow valve starts to make a horrible flatulent sound. The bottle leaves the machine with an infinitely satisfying chffff noise, like a tiny, refreshing alien disembarking from his pressurized spaceship. You’re then free to add flavored syrups (carbonating anything other than pure water is a big no-no). SodaStream is happy to sell you those syrups, of course — their Red Bull knockoff isn’t bad, and avoiding giant flat bottles of tonic water is worth some flavor sacrifices. But the last time I checked (2005) many of the other flavors were underwhelming. Oh well: soda’s bad for you anyway.
Even if you just want seltzer, you’ll need SodaStream to sell you replacement CO2. This was their real innovation: the carbonator units contain replaceable cannisters of compressed gas that are much larger than those used by soda siphons. A refill costs $25 or $30 bucks (there are two sizes — I strongly recommend the larger) and can either be delivered to your home or, as of late last year, picked up from most Bed Bath & Beyond or Ace Hardware stores. I go through two or three of the larger cannisters per year.
As you might imagine, there’s a bit of a markup on the gas. Quite a bit, in fact, though it’s still a great deal compared to the alternatives that used to exist. Still…
I work with a number of fellow seltzer enthusiasts, and more than a few of them are also people who don’t like the idea of business models based on lock-in. So once we had resolved to get a SodaStream for the office, it wasn’t long until we came across co2doctor.com.
Compressed CO2 is easy to buy, as I found out in college when I built a kegerator. Any welding supply shop will be happy to sell you the stuff — the good old boys in the Charlottesville shop asked if I was “makin’ some suds” (I was). And like any good industrial byproduct, it’s cheap: refilling one of tanks those guys use costs about the same amount as a SodaStream refill, but provides many times as much CO2.
SodaStream’s gas cannisters — they’re properly referred to as “bottles” from here on out — aren’t designed to be refilled with standard equipment. There are booby-traps built into the valves. If you want to use bulk CO2, you need to avoid those valves. You’ve got two options for doing so:
- You can connect a CO2 cannister directly to your carbonator using the FreedomOne.
- You can replace the valve on a SodaStream bottle, then use the FillStation to refill it.
Option 1 is appealing if you’ve got the space for it (SodaStream carbonators look good on a kitchen countertop; industrial CO2 cannisters do not). Our office chose the second option in order to make it possible for staff to refill CO2 cannisters for home use.
The option you select has implications for which CO2 tank you buy. If you’re carbonating directly from the tank (option 1) you need a tank that dispenses gas. If you’re refilling bottles, you need one that dispenses liquid CO2 — a so-called siphon tank, which connects the tank valve to the bottom of the cylinder via a sort of metal straw. Either type can be acquired, full, for less than $100.
Replacing the valve was pretty easy. Discharge the bottle fully by pressing in the valve pin with a pen (do this outside; wear glasses or goggles). Find yourself a vice, or a couple of friends with excellent grip strength. You’ll need a proper wrench, but once you have one the operation is easy: the valve simply unscrews. Replace it with the FreedomValve, using the supplied o-ring. Tighten it very securely.
Refilling the bottle is also easy. Once again: eye protection. Make sure all valves are closed. Connect to the tank; connect to the bottle. Open the FillStation’s smaller valve to flush any pressure in the bottle. Close it. Open the large valve on the tank. Open the large valve on the FillStation. Listen for satisfying whooshing and gurgling. The good CO2 Doctor is very insistent that you fill your bottle by weight, and that you never overfill it — but he also acknowledges that the laws of physics make it impossible to fill it to capacity using a mere siphon tank (as opposed to the exciting machinery that presumably exists at SodaStream World HQ). We weighed the bottle carefully and filled slowly, but we found that letting pressure completely equalize between the two worked just fine and left us within safety limits. Close the FillStation valve. Close the tank valve. Disconnect the bottle (there will be whooshing!). And for pete’s sake remove the FillStation from the tank, lest it tip over, break off the valve and turn everything into an episode of MythBusters.
And that’s it! At work Scott has crunched the numbers and determined that refilling bottles for home use will entail a $4 per-bottle fee. That gets you about 80% of a full charge — not bad! The $30 valve replacement will have paid for itself in just two bottles. But if you don’t have a group that wants to share a siphon tank, you might be better off using the direct-to-tank adapter (for a breakdown of cost recovery using that method, see this post). Or hell, just use SodaStream’s bottle refill service like a sane person.