The reasons behind aquarium temperature increases are not limited to the equipment we use. Sure, equipment plays a vital role, but temperatures can climb pretty high despite taking preventative measures like using external water pumps, LED lighting, and low wattage equipment. This can be due to poor air circulation over the tank, high ambient temperatures, and sunlight shining onto the tank. Improving air circulation, cranking up the A/C, and blocking out excess light can certainly drop aquarium temps, but you may need a chiller. They are expensive to purchase and maintain, but they do a great job of decreasing water temperatures.