Not sure if I can explain this right. I just set up a used 45g. It came with a lot of junk, heaters, filters ect. I'm trying to use a older heater and it doesn't fit right at the top so it's held on by a clamp that sticks to the side. It's 15" long and glass. I've heard of glass heaters cracking and frying fish. There is no markings and I was wondering about a safe level to keep the water. I'm not going to use it for ever but I'd like it to work for a while with out burning my house down.
