Apparatus for controlling algae and bio-organisms in bodies of fluids (102), such as water. The algae control system (100) includes a power unit (122) and a transducer unit (110) that includes a sonic head (114) that radiates in multiple directions. The power unit (122) connects to various power sources, including a mains supply connection (202), a solar panel array (124), and/or a battery (222). The power unit (122) is electrically connected to the transducer unit (110). The sonic head (114) includes a driver (216) and a transducer subassembly (224). The driver (216) excites the transducer subassembly (224) to emit ultrasonic waves at various frequencies in the water (102) surrounding the sonic head (114). Emissions at a high density of frequencies are enabled by the transducers (214). The frequencies include the critical structural resonant frequency for each microorganism to be controlled. The power unit (122) and driver (216) each include a processor (610, 232) in communication with each other. The processors (610, 232) store and execute a program for a selected application configuration.
