I want to add a heater to my fish tank and it has a small temp sensor. Here is a pic. It is about 4 inches long. Will this small amount of copper poison my fish. I have about 600 gallons or more of water in the system. Ron is using the same heater and he encapsulated his in a bottle and sealed it. I was thinking of just painting mine with some clear since it won't be hotter than 80 in the tank.