Fermonster PET Plastic 6 Gallon Wide Mouth Carboy with Extra Drilled Lid Review (2026)

Who this carboy is built for

This is a 6 gallon PET plastic carboy from Fermonster, built for homebrewers who like the visibility of glass but want a lighter, shatterproof vessel to carry and clean. According to the manufacturer, the body measures approximately 20 inches tall by 11 inches wide and is made from food grade, BPA free virgin PET plastic without added plasticizer. It includes an extra drilled lid alongside the standard solid one, so the same carboy can be closed with a normal airlock setup or switched to a lid with a center hole for a drilled stopper or Better Bottle style universal bung. That flexibility suits brewers who want one vessel for both primary fermentation and later stages that need a blow off tube or thermowell probe.

Build, opening and markings

The carboy has a 4 inch wide mouth opening, notably larger than a standard narrow neck carboy, which the manufacturer states reduces spillage when filling and makes it far easier to reach inside with a hand or brush for cleaning. The body is molded with smooth, ribless sides so trub and yeast have fewer places to cling, and a beveled bottom that mounds sediment toward the edges rather than spreading it flat, which helps when racking beer off the trub. It is brilliantly clear with built in 5 and 6 gallon fill markings molded into the plastic, so brewers can gauge batch volume at a glance without a separate measuring step during the boil or transfer.

The lid and seal in practice

Each carboy ships with a one piece lid that uses a rubber o-ring gasket to create an airtight seal, along with the second, drilled lid for accessories. Because the seal depends on the lid being seated evenly and tightened enough to compress the gasket, an off center or loosely closed lid can allow a slow leak of fermentation gas or, worse, let in oxygen, so brewers should check the seal each time the vessel is closed. The plastic body should also be cleaned with non abrasive tools, since PET can scratch, and scratches create hiding spots for bacteria and wild yeast that are harder to sanitize out over repeated uses.

How it compares with other plastic carboys

Against the Northern Brewer Big Mouth Bubbler, a similarly sized 6.5 gallon ported PET carboy, this Fermonster trades a built in spigot port for the extra drilled lid, so the choice often comes down to whether a brewer prefers bottom draining or top mounted accessories. Compared with the standard Fermonster 6 Gallon that ships with only the solid lid, this version's second drilled lid is the main upgrade, giving more flexibility without changing the base vessel. Against smaller 3 gallon Fermonster fermenters with a spigot and airlock built in, this 6 gallon size is aimed at full five gallon batches with headspace to spare rather than smaller test batches or starters.

Verdict and who should look elsewhere

Choose this Fermonster if you want a shatterproof, easy to clean 6 gallon fermenter with the option to switch between a plain airlock lid and a drilled lid for a blow off tube or thermowell. Brewers who want a built in bottom spigot for draining without lifting the carboy should look at a ported model like the Big Mouth Bubbler instead. Anyone who plans to scrub the interior with abrasive pads or steel wool should also reconsider, since that habit will scratch the PET plastic faster than it would a glass carboy, shortening the vessel's useful life.

Frequently asked questions