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I am not sure if you have as many suppliers in your area as we have in the South but you might try a Solar Panel supplier. We use an inline pump that has threaded input & output and is driven by a 24V motor. This pump may be just what you are looking for. I am not sure of the GPH rating but that may vary with the size of the motor you use.
The 24V isn't a problem as they use a 110 to 24V transformer.