I used 100' 3/8 o.d. tubing coiled loosely and used quick connects for all the fittings.with a valve on the return to regulate the flow which gives some control over the temp.A mag 3 is sitting it the sump/fuge.The holes drilled real clean with a wood spade style bit .
I use 120' of 1/4 o.d. tubing in my sump with direct tap water slowly flowing through it and into a drain. A solenoid on the line turns it on or off. Works well enough to drop 300 gallons with 1400 watts of light on it by 2 degrees.