The externally mounted GasMix digester mixing system from Landia reduces maintenance, as there is no need to open the digester. It can agitate the entire digester tank, preventing a crust from forming on top. Chopper pumps and a self-aspirating system reduce solids to produce more methane in less time. The system is easy to regulate and saves significant energy. In the first mixing stage, the liquid is injected into the tank’s upper half under high pressure, while new biogas is drawn from the top of the tank and mixed. In the second stage, the liquid is injected into the tank’s lower half under high pressure, causing vigorous mixing. 919/466-0603; www.landiainc.com.