i noticed that the silicon sealing the tank has a blue / teal tint to it. the only time ive seen that is when i would treat a freshwter tank with ich medication. now, the freshwater stuff i used did not contain copper (i read that if a tank has had copper-based treatments used in it, you cannot use it for a reef tank). the person i got this tank from assured me that no copper was used in this tank. what can i buy to test and make sure that no copper-based medications were used in it?