|Better Farming Series 32. Biogas 2: Building a Better Biogas Unit (FAO Better Farming Series, 1986)|
104. It may take up to three weeks or even a month for the waste in your new biogas unit to begin making gas. After that, the unit will continue to make gas for about eight weeks.
105. During these eight weeks half of the gas will be made in the first two or three weeks and the rest in the last five or six weeks.
106. If you find that too little gas is being made in the last weeks empty the unit and start again.