geothermal copper tube rez cooling

Does anyone have a link to Panhead's geothermal rez cooling method using a copper tube? Or any detailed geothermal copper tube cooling tutorials?

Here's a link.

http://www.homehydrosystems.com/system_plans/Other Hydroponics Related Designs/geothermal reservoir/Geothermal reservoir plans.html

Not to Panhead's but a better one. If he is still riding a Panhead he's way behind the times anyway.

Im looking into the copper tubing method, does anyone have any idea on the length it should be, it should be soft copper tubing right? what gph are recommend for the appropriate amount of copper tubing plus 20 ' of vinyl tubing sending and returning water from the rez to the copper tubing and back, any other hints? Help thx