The reason they are telling you to buy a new one is because heaters usually end up failing and cooking your tank. Spending the extra 5 dollars is worth it because you do not have to worry how old a heater is. Plus than you do not have to spend the gas money to go pick one up. I havent used a heater in any of my tanks in a long time. Instead I keep my a/c and heat at a decent temperature that my dogs, fish and I can be comfortable at. Adding a heater to your tank is just one more thing to fail and when they fail it sucks because they dont just shutoff, they get stuck on and just heat your tank to over 100.