For farm multi-strain Kveik, the general consensus is one level teaspoon of Kveik for 25 to 30 liters or 6.6 to 8 US gallons, and half a teaspoon of Kveik for 15 liters or 4 US gallons. Kveik thrives from this level of pitching and will not be as happy or healthy if you add any more.