Hi everyone. I' doing some peltier cooler project. A DIY mini chiller for an aquarium and I expecting the temp drop bout 5°C but it's only 1°C drop. I'm using 1 unit of 5v with 38w TEM with a heatsink attach to and a fan 12v 0.16A. The cooler part of the TEM is attach to another heatsink with an half submerge in aquarium water. Need your guys opinion.Thanks

 

Water is a unique substance in that it takes much more energy input to raise it one degree than most other substances in nature. Without knowing the size of your tank one can only guess that 38 Watts is simply not enough power to do what you want.