I started my new tank with warm water, so it didn't have a lot of work to do, but I think my new heater has melted the bracket on the suction cup. I think it melted its internal temperature indicator, as well--it's all warpy and hard to read.
I bought one that was appropriate for my tank, so it isn't trying to work too hard. It's a common brand, easy to find at most big pet stores.
Any recommendations for a replacement?