I supposedly have an aluminum radiator, but I am not so sure anymore. I have a waterblock that I know is aluminum because I made it myself. Well, after my watercooling setup has been off for a while, bubbles seem to build up in the radiator. There are no leaks anywhere in the system. The setup is completely closed and includes a water resevoir. When I opened the resevoir, lots of air and water flew out because pressure had built up somehow. I think something is reacting with the metals and creating a gas, which built up the pressure. Does this happen when there is copper and aluminum in the same system? Is there something that I can put in my water to prevent this? Thanks.