The aquarium heaters that you can buy off the store shelf are practically worthless if your aquarium is anything more than a goldfish bowl. While they are not very expensive, you certainly get what you pay for from a painfully limited selection. The more expensive aquarium heaters that you purchase over the Internet are not much better.
The truth is that the temperature in your tank must be kept stable, especially in salt water tanks. Failing to maintain proper temperatures could leave you with a host of problems, ranging from frustrating to devastating. Unfortunately, a standard submersible heater is not sufficiently stable. Nevertheless, a solution lies with the Eurotherm 2132.
The Inadequacy of the Tube Heater
A glass tube heater has a bi-metallic strip, which acts as a temperature sensing device. The problem is that the sensor is located inside the heater. It does not make sense that it would be able to accurately measure the temperature of the water.
An aquarium heater is designed with the intent of keeping the temperature inside the tube relatively constant. This is assuming that the heat load of the aquarium stays constant and the water temperature is pretty steady. However, the ambient temperature in most places varies considerably, which means the heat load on the aquarium fluctuates. Therefore, submersible heaters are not the ideal instrument for regulating aquarium temperature.
Adding Some Distance
The answer is using a sensor that you mount at a distance from the actual heater. This way, the sensor measure the temperature of the water, as opposed to the temperature of the heater. Ready-made systems can be purchased, but can be quite expensive and you do not get your money’s worth. Instead, you can use the Eurotherm 2132, which is a PID controller that features a platinum resistance temperature device.
Simply mount the controller in a box designed to house electrical components and wire the solid-state relay so that it controls the outlet. You will still be using the submersible aquarium heater. Put the heater on the highest temperature setting, so it will come on when the relay switch sends power according to the Eurotherm 2132 configuration parameters.
The controller is packed with options for various modes of operation. One of the best features of the Eurotherm 2132 is the PID loop parameters auto-tune function in order to determine the ideal PID parameters.