Review on 🐠 Betta, Bowl, and Aquarium Hydor Slim Heater by Jackie Archuleta

I have two of these 15 watts for my two 3.5 gallon cockatiel tanks for a year. I have about an inch of gravel that I buried the heaters under, they are in the middle of the bottom of the tanks. Each tank has a small skin and random foliage. The tanks have a filter and a light. At my home, the temperature varies between 64 and 78 degrees throughout the year, depending on the season and time of day. These heaters kept my tanks between 78 and 82 degrees at all times. My males are very active, healthy and happy. I haven't noticed any slime build up on them or the cord. Speaking of the cord, it's long, making it easy to get to an outlet and keep it in the tank. The included suction cups help keep the cable in place. I've tried lower wattage but it wasn't enough and I haven't heated 3.5 gallons of water above 72-74 in my house in the summer when my house was usually between 76-79 degrees. I recommend this 15w for any tank up to 3.5 gallons more and I can't say as I don't have tanks larger than 3.5 gallons. I use this in Top Fin: Enchant 3.5 gallon tanks.