I wish someone would build a cheap ultrasonic flow meter that you can touch to the outside of a hose so that these cooling questions could be less guess work.
My fuzzy memory was that I had to pay $1200 in 1981 dollars for an outside the pipe ultrasonic flow meter, but it paid for itself many times when pumping 400 tons per hour of mixed rock sizes through a 12 inch ID pipe with 12,000 gallons per minute of water.
