The Brew Cooler is a waterproof, insulated cooling bag to keep correct fermentation temperature in fermenters up to 30L. Perfect if you dont have space or possibility to place your fermenter in a temperature controlled refrigerator at home.How the Brew Cooler worksThe function is simple, place your fermenter inside the Brew Cooler and add frozen water bottles (preferrably plastic) inside the Brew Cooler to reduce and keep the correct fermentation temperature. The volume of frozen water in the plastic bottles determines how many degrees below room temperature the fermenter will be kept at. The frozen water bottles should preferrably be replaced every 24 hours, or when needed.1. Place the Brew Cooler at a suitable location in your home. Place your fermenter with wort inside the Brew Cooler.2. Place the correct number of frozen water bottles inside the Brew Cooler according to the Temperature Chart below.3. Close Brew Cooler zip locks.4. After 24 hours, exchange the frozen water bottles for new ones.Temperature Chart: Choose the correct fermentation temperatureThis chart gives examples of the number and size of frozen water bottles that is needed for a given temperature reduction in the Brew Cooler for 20L beer.One 1-liter bottle reduce 1,5°C.Two 1-liter bottles reduce 3°C.One 1,5-liter bottle reduce 2°C.Two 1,5-liter bottles reduce 4°C.Three 1,5-liter bottles reduce 6°CFour 1,5-liter bottles reduce 8°C.One 2-liter bottle reduce 3°C.Two 2-liter bottles reduce 6°C.Three 2-liters bottles reduce 9°C.Four 2-liter bottles reduce 12°C.These temperature reductions are valid for 20L beer in the fermenter. As can be seen, the temperature reduction is about 1,5°C per liter frozen water. The maximum temperature reduction that can be archieved is about 15°C.Example: If your home ambient temperature is 21°C and you want to ferment 20L ale at 18°C, add one 2-liter or two 1L) frozen plastic water bottle together with your fermenter in the Brew Cooler. Exchange every 24 hours and repeat at least the first 3-4 days during the primary fermentation. If your brew 10L then about half the volume, 1-1.5L frozen water, is enough. What is the correct fermentation temperature?To get your home brew to taste as good as possible its important to control the fermentation temperature. An ale can theoretically be fermented at room temperature, 20-22°C, however it will taste the cleanest when fermented around 18°C, at least the first 3-4 days of fermentation. Lagers should be fermented at 10-12°C. Saisons can be fermented at high temperatures, 20-35°C, depending on the flavour profile you want.Brew Cooler 30L specificationsHeight: 60 cmLength 40 cmWidth: 40 cmMaterial: Tough black polyester Kraftig svart polyester with insulation and a grey water proof inner liner.Carrying strap: The Brew Cooler is equipped with an adjustable carrying strap.