Wanted to post my experience. I believe it's much the same as others who have contributed to this thread.
My GPU took a dump so I had to RMA it and decided to redo the tubing in my loop. I have Durelene tubing ordered from Sidewinder Comps off Amazon Marketplace.
These are pictures after two months using brand new waterblocks (Heatkiller GPU & Raystorm CPU), brand new bitspower Nickel barbs, & a brand new XSPC RX360 rad.
Coolant is just Safeway Refreshe Distilled water w/Deadwater & 2 silver killcoils inside the reservoir.
This is the loop after I cut out the GPU lines & was draining the water out. Notice the yellow tint.
More pictures of the used tubing.
And some pics of the used tubing compared to brand new.
Also something interesting to note, the following pic is part of the line where I had a drain valve installed. There was no running water though this part of the line. To the right you can see the T-splitter and this tubing went strait down to the bottom of the case. The coolant flows straight through the T-splitter back into the reservoir/pump.
I didn't have the patience to order some other tubing and see how it works, my rig was down for nearly 3 wks waiting for the GPU RMA. I rebuilt the loop with the same Duralene tubing and this time am using H20 brand Distilled water w/PT Nuke & same 2 silver kill coils. I know that recent posts have suggested the additives are causing the plasticizer but I'll see how this goes.