Bumbler,
Great design and execution.
I can visualize a slightly different design that has one shaft driving two sets of rollers running on two separate tubes. That would synchronize flow to the sparge arm with flow from the MLT to the boil kettle. Building this out of stacked sheets of plywood might lend itself to multiple pumps for greater versatility. It looks as if your motor would have plenty of power.
Great design and execution.
