The AS3020 cooling tower controller monitors the conductivity of the water, and if during a given set time it should exceed a predetermined sediment level, then the flush valve will be opened. Two level-switches can also be connected to the controller which control an inlet valve. This inlet valve opens when the tank is empty. Depending upon the programming the flush valve can be closed or it can stay open until the tank is full again. If this happens, the system will switch to the refill stage. When the tank is full, then the inlet valve will be closed off and the conductivity will once again be controlled.