I have a few of these from 50w to 200w. My only complaint is that they keep the water at 77 instead of 78 (tested with multiple thermometers and controller probes). But that's not so important. 77 is suitable for almost every type of tank. They heat water and keep it at a constant temperature. I use them in a reef tank and two freshwater tanks. I haven't had a single failure, but I keep them connected to temporary controllers in case they break. I've spent more money on other supposedly good quality heater controls and they all failed within 6-12 months (hence the importance of the heater controller). After years of experience with a wide range of heaters, these simple pre-configured Aqueon heaters are in all of my flagship aquariums. Because they're so cheap, I keep a few spares as backups. But like I said, I haven't had a single failure yet.
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