Last updated:
The Catalyst Fermentation System from Craft a Brew is one of the more innovative plastic fermenters to emerge in the homebrewing market, a conical-bottom design in food-grade Tritan plastic that brings the yeast separation benefit of stainless conicals to a significantly lower price point. I’ve brewed multiple batches through the Catalyst and the design execution is thoughtful in some ways and limited in others, which is worth understanding before deciding whether it fits your brewing practice.
Catalyst Fermentation System design and features
Construction: 6.5-gallon Tritan plastic (BPA-free, food-grade copolyester) conical-bottom fermenter with a flat top lid. Tritan is more impact-resistant than standard PET and has better clarity than HDPE, the Catalyst is visually transparent, allowing monitoring of yeast layer and fermentation activity without opening the vessel. Conical bottom: the cone angle collects settled yeast and trub at the apex, where a removable collection vessel (a small jar-style container) attaches via a threaded coupling. The collection jar allows yeast harvesting by removing it from the cone base without disturbing the beer layer above, the primary design feature that distinguishes the Catalyst from standard bucket fermenters. Key features: Collection vessel: a glass jar (or later versions use a plastic jar) that threads onto the cone bottom. After fermentation, yeast and trub settle into the jar, which can be removed and replaced with a clean jar for yeast harvesting or simply left in place. The jar attachment maintains a sealed connection during fermentation. Rotating racking cane: an adjustable tube inside the fermenter that can be positioned at different heights to transfer from above the yeast layer without a siphon, allows gravity-driven transfer without oxygen pickup from siphon operation. Stand: the Catalyst requires a stand to elevate it above the receiving vessel for gravity transfer, the included stand positions the fermenter at counter height with clearance for a jar or pitcher below the collection vessel. Airlock port in the flat lid. No pressure fermentation capability, Tritan plastic and the threaded collection vessel connection are not rated for positive pressure. Capacity and batch sizing: The 6.5-gallon vessel accommodates 5-gallon batches with approximately 1.5 gallons of headspace, adequate for most fermentations but tight for very vigorous Belgian or Hefeweizen fermentations that produce large kräusen heads. A blowoff tube setup is recommended for these styles.
Performance and practical limitations
Yeast harvesting in practice: The collection vessel system works as described, yeast settles into the jar and can be removed and refrigerated for repitching. The quality of harvested yeast is better than bottom-draining a flat-bottom fermenter because the cone geometry preferentially collects the densest-settled yeast in the jar with reduced trub contamination in the upper yeast layer. However, the collection jar is small (approximately 150–200mL capacity), for high-flocculating strains that produce large yeast cakes, some yeast remains distributed across the cone walls above the jar. Transfer performance: The rotating racking cane is the Catalyst’s most useful practical feature. Being able to draw beer from above the yeast layer without siphoning significantly reduces yeast pickup in the transferred beer and eliminates siphon-related oxygen pickup. Gravity transfer from the elevated stand into a keg or bottling bucket works well. The seal around the racking cane port must be checked and maintained, a leaking seal allows oxygen ingress during transfer. Cleaning: The Catalyst’s wide-mouth flat lid allows easier interior cleaning than a carboy. The cone interior requires careful attention, a cone-specific brush or PBW soak reaches the angled surfaces. The collection vessel jar removes for separate cleaning. The threaded connection between cone and collection jar must be thoroughly cleaned as the threads can accumulate residue. Comparison to stainless conicals: The Catalyst provides genuine conical fermentation benefits at $80–100 versus $200–400 for stainless conicals. The trade-offs: Tritan plastic scratches and degrades over time, is not pressure-capable, and lacks the indefinite lifespan of stainless. For brewers evaluating whether they want conical fermentation before committing to stainless cost, the Catalyst is a practical evaluation step.
Common Questions
Is the Catalyst worth buying over a standard bucket fermenter?
The Catalyst is worth the premium over a standard bucket specifically if yeast harvesting and clean transfers are priorities in your brewing practice, these are the two features it delivers meaningfully better than a $10 bucket. If you repitch yeast regularly and want cleaner yeast collection than scraping the bottom of a bucket, the Catalyst’s collection vessel makes harvesting easier and the collected yeast is cleaner. If you currently use a siphon for transfer and want to eliminate the siphon’s oxygen pickup and labor, the rotating racking cane is a genuine improvement. If neither of these features matters to your current process, if you use fresh yeast every batch and don’t mind siphoning, the Catalyst’s $80–100 premium over a $10 bucket produces beer of identical quality with more complicated cleaning. The Catalyst is also not the right choice if your next equipment step is pressure fermentation and closed transfer, since it’s not pressure-capable. In that case, the $30–60 premium over a bucket is better directed toward a FermZilla All Rounder or used corny keg that enables pressure capability. Where the Catalyst fits well: brewers who want conical convenience and yeast harvesting without the full cost of stainless, who don’t need pressure fermentation, and who value the visual clarity of the transparent Tritan body for monitoring fermentation without opening the vessel.
