I had two aquariums for 3 years and never had any problems then I added these heaters to my tank and then dewormed as many worms. Luckily they were only on the lid of the tank so I could get rid of them but I don't even know if there are worms in my tanks. I took the heater out of one tank and there were no worms, the other tank still had worms. Do not buy this product! And heaters don't go above 73 Fahrenheit
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