## How do you calculate flowrate exiting a pipe?

It has been several years since I have dealt with fluid mechanics. I have a 4hp pump that circulates the water in a 4ft swimming pool. A 2in pipe is connected to the outlet which runs up about 1ft. It passes through a shutoff valve and is then split into two streams, both 2in pipe, by a Y-fitting. These two pipes continue to run vertically for another 2ft until they run into a 90° elbow, which turns the flow horizontal. There is a nozzle after another 1ft of pipe that reduces both streams to 1in. I need to calculate the flowrate exiting the two nozzles.

I would like to know how to calculate this precisely, but for now I just need an estimate. Can I assume that the Y-fitting splits my stream evenly into two equal flowrates? Will the elbow significantly reduce my flowrate, or is it negligible in comparison to the reducer?
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