The variable speed version of the popular O-Plus series! Specially designed for underwater applications. With the external controller you can adjust the flow (and thus the energy consumption) from 30% to 100%. The controller can also start/stop the pump (pause button). Provided with synchronous motor and weatherproof ceramic shaft for long time use. Automatic power-off protection when running dry. When the impeller is blocked it will go into a "lock" position in which the pump does not use power and waits until the blockage is gone. This will prevent a motor burn out.