--- title: How to Carbonate Hard Seltzer to a Repeatable Target url: https://getfizzwizz.com/how-to-carbonate-hard-seltzer/ date: 2026-11-09T16:40:47+00:00 modified: 2026-11-09T16:50:03+00:00 lang: en_US --- # How to Carbonate Hard Seltzer to a Repeatable Target Hard seltzer is a clean, light base, so the bubbles carry the palate and any miss in carbonation shows in the first sip. A seltzer that lands a half volume low tastes flat, and one that lands a half volume high can pour as foam. Knowing how to carbonate hard seltzer to a set target is what turns a good batch into a batch you can repeat. Force carbonation is the standard method. CO2 goes into cold liquid under pressure until the liquid holds the level you want. This guide covers the target level, the reasons seltzer carbonates differently from beer, the keg and bright tank methods, and how to hold the level through packaging. Each step comes with the numbers you need to set a pressure and check the result, and the guide closes with a troubleshooting section for flat and foamy pours. ## What Carbonation Level Should Hard Seltzer Be? Carbonation is measured in volumes of CO2. One volume is one litre of CO2 gas dissolved in one litre of liquid, which works out to [about 2 grams of CO2 per litre](https://journals.flvc.org/edis/article/download/118020/124629/202281). A seltzer at 3 volumes holds roughly 6 grams of dissolved CO2 in every litre. Reference points help place that number. A typical lager sits at 2.4 to 2.6 volumes and British ales at 1.5 to 2.2. [Club soda and tonic run from 2.5 to 3.5](https://journals.flvc.org/edis/article/download/118020/124629/202281), high-carbonated colas reach 3.5 to 4, and German wheat beer is close to 5. The carbonation levels for hard seltzer that most producers settle on run from about 2.5 to 3.5 volumes, which puts seltzer in club soda territory and above most beers. A seltzer is light and clear, so the sparkle is the main sensation on the palate, and a level above beer suits it. The level can only climb so far before packaging and dispense start working against you. Water at 5°C (41°F) holds [3.69 volumes at 25 psig and 4.16 at 30 psig](https://journals.flvc.org/edis/article/download/118020/124629/202281). Each step up means a higher keg or tank pressure, packaging rated for that pressure, and dispense lines long enough to calm the pour. Pick one target inside the range for your product, write it on the batch sheet, and use that same number every time. ## Why Hard Seltzer Carbonates Differently Than Beer Henry's law says the amount of gas a liquid holds rises with pressure and falls as the liquid warms. In practice, every temperature has exactly one equilibrium pressure for a given carbonation level. That is [how pressure and temperature set the carbonation](https://getfizzwizz.com/how-it-works/), and the FizzWizz works backwards from your target to that one pressure. The numbers show how tight the relationship is. Water at 5°C (41°F) holds 2.76 volumes at 15 psig, and at 10°C (50°F) it takes 20 psig to reach 2.77. Five degrees of warming costs about 5 extra psig to hold the same level. On the ASBC chart, [3.0 volumes needs 16.7 psig at 38°F and 14.0 psig at 34°F](https://cdn.brewersassociation.org/wp-content/uploads/2021/07/22093927/Facts_About_Draught_Beer_Carbonation.pdf). A few degrees in the cold room move the pressure by several psi. Sugar and alcohol shift the numbers too. [Sugars lower the solubility of CO2 in water](https://www.nature.com/articles/s41598-025-16266-0), and the more sugar in the liquid, the lower it goes. Alcohol changes it as well. The chart assumes a gravity of 1.015 and 4.8% ABV, so a seltzer with a different gravity or a fruit addition sits a little off its figures. A seltzer that looks finished can still pour flat. The headspace reaches chart pressure within minutes, while the liquid takes far longer to absorb the gas, so a gauge that reads right can sit over a liquid still short of target. Once the keg drops to serving pressure, the pours show it. A clear base shows every missing tenth of a volume, so a quick shake that lands a beer close enough often leaves a seltzer short. Hard seltzer carbonation depends on giving the liquid time or agitation, and on checking the result against the chart. ## Get the Base Ready Before You Carbonate Four things need to be true before any gas goes in, and the first is a finished fermentation. A stable gravity reading across two checks a day or two apart tells you the yeast has stopped. Carbonating a base that is still fermenting makes pressure unpredictable. The second is a clear base. Cold crashing, fining or filtration remove the haze and yeast that give dissolved gas places to form bubbles, so a cleared seltzer holds its gas and pours calmer. The third is flavour additions that cannot ferment. Extracts and flavourings can go in as they are. Fruit, juice or sugar must be stabilized first, because fermentable material can restart fermentation in the keg or can and push pressure past your target. The fourth is temperature. Chill the product close to freezing before carbonating. Cold liquid takes the gas at lower pressure, and the chart pressure only holds when the temperature holds. A keg or tank still warming from the cellar will drift away from the number you set. ## Bottle Conditioning or Force Carbonation? Bottle conditioning is the slow route. Priming sugar goes into the bottle, the yeast eats it, and the CO2 it makes dissolves into the liquid. Every gram of sugar the yeast consumes yields [about 0.46 g of CO2 and 0.48 g of ethanol](https://journals.flvc.org/edis/article/download/118020/124629/202281). The method works best at 80 to 100°F, takes weeks, leaves yeast sediment in the bottle, and needs pressure-rated bottles for higher carbonation levels. A stabilized seltzer has had its yeast stopped or removed, so priming sugar has nothing to ferment. A seltzer backsweetened with fermentable fruit, juice or sugar carries a different risk. Any yeast still present can restart fermentation in the sealed bottle and push the pressure past what the glass can hold. For seltzer, that rules bottle conditioning out for most finished products. Force carbonation is the method most producers use. [CO2 pushed through a porous stone](https://journals.flvc.org/edis/article/download/118020/124629/202281) is the most used method in industry and can carbonate large volumes within hours, and agitation raises the rate significantly. The product then has to be served from the vessel or packaged under pressure, or the CO2 escapes. Producers choose seltzer carbonation by force for four reasons. It works on stabilized and backsweetened product. It reaches a chosen volume level instead of whatever the yeast produces. It leaves no sediment. It takes hours or days where bottle conditioning takes weeks. ## How to Force Carbonate Hard Seltzer in a Keg Start with a carbonation chart. Find the product temperature in one axis and your target volumes in the other, and read off the gauge pressure. On the ASBC chart, 2.5 volumes at 38°F needs 11.3 psig, and 3.0 volumes at 38°F needs 16.7 psig. Chill the keg first, and purge the air from the headspace with a few short bursts of CO2 before you set the pressure. ### Set and Forget Set the chart pressure for your serving temperature, connect the gas, and wait. The liquid settles at the equilibrium for that pressure and cannot overshoot, which makes this the slowest method and the most accurate. Plan on days. ### Burst Carbonation Burst carbonation uses a higher pressure for a set period, usually overnight, and then drops to serving pressure. It gets a keg ready sooner. The time and the pressure have to be matched to your keg and temperature, and a burst left on too long ends in an over-carbonated seltzer. Record the pressure, the hours and the result for the first few kegs so the method repeats. ### Shake or Rock the Keg Agitation under pressure is the fastest way to move gas into liquid. Rock the keg for short spells with rests between them. The gauge pressure falls as the liquid absorbs gas, and when it stops falling between rocks, the liquid has caught up. Stopping early leaves the seltzer short, and carrying on at high pressure overshoots. Once the target is reached, drop the regulator to serving pressure for your serving temperature. Seltzer needs a higher pressure than beer, so the dispense lines have to be balanced to it. At 38°F, 3.0 volumes holds at 16.7 psig where 2.5 volumes holds at 11.3. Lines sized for the lower pressure let the higher one push through as a jet and a glass of foam. Longer or narrower lines add the resistance that settles the pour. ## How to Carbonate Hard Seltzer in a Bright Tank At production scale, the same physics runs on a larger vessel. Chill the tank and the product first. Oxygen picked up after fermentation shortens shelf life, so [purge oxygen before carbonating](https://getfizzwizz.com/pre-scrub-dissolved-oxygen/). Then carbonate through a stone, whose fine pores make small bubbles that dissolve quickly. Set the finish pressure for the product temperature and hold it there. Holding it is the harder part, because temperature drifts. A tank that warms overnight needs more pressure to hold the same carbonation. As temperature rises, [gas solubility falls and product pours foamy and then goes flat](https://cdn.brewersassociation.org/wp-content/uploads/2021/07/22093927/Facts_About_Draught_Beer_Carbonation.pdf). If temperature falls, the product ends up over-carbonated. The FizzWizz handles that work in the tank. You enter a target in volumes of CO2. The WizzTemp probe, which the system requires, reports product temperature, and a pressure transducer reports tank pressure. The FizzWizz calculates the finish pressure, adds CO2 through the WizzStone-Combo stone, whose pores measure 0.5 micron, and holds the level until you are ready to package. It keeps recalculating as conditions change. The FAQ confirms it [works for seltzer as well as beer, cider and kombucha](https://getfizzwizz.com/faq/). Pre-scrub mode prepares the system before carbonation by purging the lines and bringing the circuit to a known state. Packaging puts the carbonation at risk. Product leaving the tank for a filler loses CO2 and foams if the pressure drops, so the tank pressure has to hold through kegging, canning and bottling. Head Pressure mode [keeps the product at its target carbonation through packaging](https://getfizzwizz.com/features/) by regulating pressure between the tank and the filling system. The bottom of a tank also reads higher than the head gauge, a gap the article on [head pressure and hydrostatic error](https://getfizzwizz.com/head-pressure-and-hydrostatic-error/) works through. The FizzWizz lists a [10 to 30 percent reduction in CO2 use and 70 to 90 percent less product lost](https://getfizzwizz.com/) to short fills or overfills. Canned seltzer needs one more plan. Cans warm on the shelf and the pressure inside climbs with temperature, so the product has to be stabilized against fermentation and the can's pressure rating sets the ceiling for your target. ## Troubleshooting Flat or Foamy Hard Seltzer Flat or foamy seltzer usually traces back to a short list of causes. Product warmer than the chart assumed is the most common one. If the liquid sits at 38°F while the pressure was set for 34°F, 3.0 volumes needs 2.7 psi more than you gave it. Check the actual temperature at the time you set the pressure. A temperature reading that runs warm leaves the product under-carbonated, because the system calculates less CO2 than the product needs. The ice-water test on the [WizzTemp probe](https://getfizzwizz.com/how-it-works/) confirms its accuracy in a couple of minutes. A dirty carbonation stone is one of the leading causes of low carbonation. Plugged pores make large bubbles that do not dissolve. Regular [ultrasonic cleaning of the stone](https://getfizzwizz.com/ultrasonic-stone-cleaning/) clears the pores that soaking leaves behind. Dispense lines that are too short for the pressure turn a correctly carbonated keg into foam. Add line length or resistance until the pour settles. Gauge pressure not corrected for altitude leaves the product low. Carbonation follows absolute pressure, so [add 1 psig for every 2,000 ft above sea level](https://cdn.brewersassociation.org/wp-content/uploads/2021/07/22093927/Facts_About_Draught_Beer_Carbonation.pdf). Gas lost during packaging shows up as cans or kegs below target after a correct tank reading. Hold head pressure through the whole fill, and measure a few packaged units against the tank. Carbonation that matches the set target batch after batch comes from measured temperature and pressure. If you would like help carbonating seltzer on your equipment, [talk to our team](https://getfizzwizz.com/contact/) and we will go through your tanks, stones and packaging line with you. You can also [find your kit](https://getfizzwizz.com/find-your-kit/) to see which FizzWizz setup suits your tanks.