Abstract: Two apparatuses are disclosed for providing a dynamically varying water surge in a salt-water reef aquarium. The first apparatus is a micro-controller based variable frequency reef surge drive 100 for an AC permanent magnet synchronous motor (PMSM) submersible aquarium pump. Drive 100 comprises voltage conversion circuitry 105, xmicro-controller 110, reef-surge generation program 115, variable frequency drive 118, mode switch 130 and tidal cycle switch 135. Three user-selectable modes of operation are provided: a random frequency mode, a fixed-program mode and a tidal mode. A second apparatus comprises a novel submersible AC PMSM pump with dual impeller assemblies and dual input and output chambers for supporting forward and reverse flow through an AC PMSM pump.

Abstract: Two apparatuses are disclosed for controlling the speed of an AC synchronous motor-pump utilizing a series of stepped voltage pulses at the driving frequency. The first apparatus is an isolated variable frequency drive comprising step-down transformer 100, full wave rectifier and filter 101, micro-controller 108, driving-voltage array generator 102, gate driver 107, inverter bridge 103 and step-up transformer 104. The second apparatus is a non-isolated high voltage variable frequency drive comprising full wave rectifier and filter 201, low voltage, dual output power supply 205, micro-controller 208, driving-voltage array generator 202, gate driver 207 and inverter bridge 203. Methods are given to determine voltage array values and pulse times to generate a stepped voltage approximation of a sine wave driving waveform.

Abstract: A vertical water wall assembly (100) for generating dynamically changing water patterns in a contained channel (114) behind a viewing surface. The water wall assembly includes a translucent front sheet (110) directed toward a viewing space with a rear side containing a multiplicity of concave depressions (111), and a rear sheet (140) disposed behind and in proximity to the front sheet that in part acts as a contrasting background. The edges of these sheets are sealed (120, 122) and water is made to flow in the space defined between the two sheets, entering at the top of the sheets (135) and exiting at the bottom of the sheets (150). The flow of water into the water wall at the water inlet (125) is time varying and is preferably computer-controlled (190). In operation water flowing in the contained channel (114) of the water wall takes dynamic, chaotic pathways through the multiplicity of concave depressions (111).

Abstract: A vertical water wall assembly (100) for generating dynamically changing water patterns in a contained channel (114) behind a viewing surface. The water wall assembly includes a translucent front sheet (110) directed toward a viewing space with a rear side containing a multiplicity of concave depressions (111), and a rear sheet (140) disposed behind and in proximity to the front sheet that in part acts as a contrasting background. The edges of these sheets are sealed (120, 122) and water is made to flow in the space defined between the two sheets, entering at the top of the sheets (135) and exiting at the bottom of the sheets (150). The flow of water into the water wall at the water inlet (125) is time varying and is preferably computer-controlled (190). In operation water flowing in the contained channel (114) of the water wall takes dynamic, chaotic pathways through the multiplicity of concave depressions (111).