The maximum temperature at which acrylic plastic can be subjected to for any period of time is 180°F/82.22°C to 200°F/93.33°C. The material softens when heated to temperatures above 260°F/126.66°C. Applications subjected to high heat sources should be avoided or temperatures checked to allow for an adequate safety factor. An alternative clear plastic to use would be Tuffak Polycarbonate with a service temperature of 270°F/132.22°C.
So keep this in mind when cooling your system. Also, not sure about any polycarbonate tanks, but it may be an alternative for high temp systems? Just my $.02.