D-D Cooling fan 

Long-life ball bearing fans - reduces noise + increases reliability.

6 Fan:

• Quiet, long life fans, with ball bearing and brush-free motor
• Fits tank rim up to 12 mm 
• 90 degree adjustable brackets to adjust fan angle
• 12 V low voltage power 8.6W
• Total air volume: 180,000 l/h
• Corrosion proof plastic construction
• Best results obtained by fan blowing air across water surface

High temperatures in an aquarium can cause stress and disease. Not everyone has the budget or space for a refrigerant chiller and so a simple solution is to chill your tank by evaporative cooling.

This low-cost solution simply involves blowing a stream of air over the surface of your tank or sump to increase evaporation, which creates evaporative cooling.