Have you thought about the pressure caused by the hoses when they try to straighten themselves out when you start pumping around that massive amount of water?
The hoses will get really really hard due to the pressure.
I thought of this as i saw a rolled up garden hose getting really stiff when waterpressure was applied. I tried to bend the hose before and after pressure was applied, and it was alot more difficult to bend it when the water was flowing through.
Not sure if this applies to a water cooling loop tho, food for thought anyways.
Correct me if im wrong!