John,
I found this today and thought I would post it for you. I think you already solved your flow problem but here it is:
http://www.thermexcel.com/english/ressourc/pdcline.htm
Flow rate in pipes
Flow rate in pipes
Yes I did, thank you. I ran the water backwards through the laser and power supply and all is well. It seems there may have been a small restriction in the laser or power supply that required a higher water pressure for the correct flow rate. Now the pressure is regulated and all is well. Thanks again.