Time to Build a New Counterflow Chiller

[GHawk]

After 20 faithful years of service I think its time to retire the old chiller a build a new one. A coupling broke and I got a good look at the copper tubing outside wall and wow! the funk built up on the tubing. After seeing that I'm surprised it's not had corrosion leak through yet.
Anyways, it's copper tubing is 3/8" OD and I have since moved to a single tier system using a 1/2" output size pump. I'm using 3/8" ID high temp silicone tubing that can stretch over the 1/2" barbs and easily fit onto the chiller but I've always hated that the blockage in my system's flow rate has always been the chiller.
I've been using frozen 2L bottles in a cooler of water after a re-circulation of ground water.
Question
Which is better - using 3/8" OD at 50' or 3/8" ID at 20'?
I'm thinking the better flow rate would process more volume in a re-circulation using the larger tubing, even over a shorter distance. Then, of course switch over to the ice water. Maybe even work the old tubing into the run sitting in the ice water.
Thanks

 

[GHawk]

Edited

 

[apache_brew]

My counterflow chiller is 25'. It's 3/8" copper inside a heavy duty garden hose and full flowing, never had any issue with clogging. It's only able to get me down to 70-75F with by tap water temperatures (around 60F year round) from boiling (which is great) so I've since incorporated my old 25' immersion copper coil in series downstream of the counterflow for final chilling. The copper immersion chiller now sits in a cooler filled with ice water and I can get down to 50F with 40 lbs of ice and constant agitation of the immersion chiller.

Given I know how my setup performs now, I wouldn't bother with the clunkiness of a 50' counterflow because I know I would still need the secondary chiller to get to lager pitching temperatures. So I would say stick to a 25' length if you plan to do something similar. As far as fittings and hoses go, I love my 1/2" id 3/4" od silicone brewing hoses with camlock fittings Stainless Steel Camlocks As far as connecting the copper to the hoses, stainless compression fittings are great 1/2" NPT x 3/8" Tube Compression adapter SS I use the delrin ferrules and like them. Buy extra because they're dirt cheap. But you can also use the stainless ferrules, just be careful not to crush the tube too much.