Heating Your Saltwater Aquarium
Adapted From: Saltwater Aquariums For Dummies
Most fish and invertebrates are cold-blooded animals. That means their body temperatures are the same as the temperature of the waters they live in. In general, their bodies function best at specific water temperatures and, therefore, all fishes have temperature preferences that depend on where they originate.
Based on their temperature preferences, fishes are sometimes grouped in general categories. Temperate fishes include many species that inhabit cooler waters. If you set up a coldwater aquarium, it will likely contain temperate fishes.
However, the most common fishes in the marine aquarium are tropical coral reef species. The term tropical refers to natural habitats where the waters are warm throughout the year. It should come as no surprise, therefore, that you must heat your aquarium water to a specific temperature range. This is the job of an aquarium heater. This essential piece of equipment maintains your aquarium water at a constant temperature, regardless of the room temperature.
Feelin' hot, hot, hot
Suppose you live in a warm place, like Florida, year 'round. You may be thinking that you don't need an aquarium heater. Not true. Remember, fish that live in the tropical seas of the world experience few changes in the temperature of the water that they live in. In your aquarium, therefore, you want to mimic the natural environment and maintain as constant a temperature as possible.
Even though your fish and invertebrates can tolerate a range of water temperatures, water that fluctuates even a few degrees can stress your animals and possibly kill them. In Florida, the outside temperature isn't always constant — it, too, fluctuates. This ultimately creates problems for your pets if you don't have an aquarium heater.
Unless you're planning to set up a coldwater aquarium of temperate fishes or invertebrates, tropical marine fish and invertebrate species require that the aquarium temperature be maintained at 75 to 79 degrees F. However, this range depends entirely on the species you choose, so consult your local pet dealer or one of the many fish encyclopedias for the temperature requirements of your specific pet. Make sure that you don't mix species that have very different temperature preferences.
Understanding aquarium heaters
As you can expect, many heaters are available on the market for today's home aquarium. Some designs are clearly better than others, but the most popular aquarium heaters work off the same principles and have many parts in common.
With the exception of some specialized heater designs that are relatively uncommon, a basic aquarium heater looks like a big test tube with a bunch of wiring in it and an electrical cord coming out of it. This wad of wiring is actually a heating coil contained in a glass tube that gets submerged in your aquarium. (The extent to which it is submerged depends on the type of heater.) Of course, the heating coil has to be turned on and off, and this is the job of the thermostat, the mechanism that usually determines the quality of the heater. You can set the thermostat with the control knob, and you know that the heater is operating because an indicator light fires up.
Taking a peek at types of heaters
By knowing the basic parts of a heater (see the preceding section), you can more easily discern the differences between the various types to help you decide on the right one.
Hanging heaters
A hanging heater is also referred to as the clamp-on, clip-on, or semi-submersible heater. This is the oldest style of aquarium heater and has been around since the 1970s. As you may expect, the hanging heater is so named because it hangs on the upper part of the aquarium clamped to the rim of the tank. The glass body of the heater is submerged in the aquarium, but the controls remain out of the water.
Although these heaters are the least expensive, they also tend to be the most primitive and are not the best choice for the saltwater aquarium. First, their placement at the top of the water column isn't the most efficient location for heat exchange. This location also makes them extremely vulnerable to being disturbed by both you and the tank's inhabitants. The more either of you bang into the heater, the higher the chance that it will be damaged (the glass body can crack). These heaters also tend to have less efficient thermostats for controlling their operation. A damaged heater is a dangerous electrical appliance for all living things near it. Remember, electricity and water don't mix!
After you've made such a significant investment in your aquarium, don't jeopardize the success of the entire system by saving $20 with a cheap heater. Many of your tank's inhabitants are worth more than the amount you'll save!
Submersible heaters
A submersible heater (shown in Figure 1) is the preferred heater choice for the saltwater aquarium. Also known as an immersion heater, the submersible heater is placed fully in the aquarium in any location that you desire. This means that you can put it near the bottom, out of the way of the aquarium's inhabitants, out of your view, and in a more efficient location for heat dispersion. You can even put the submersible heater in the sump of your trickle filter, keeping it completely out of the way of the aquarium. In addition, most submersible heaters have advanced thermostat controls that make temperature selection and control easier.
Figure 1: A submersible heater.
Place your heater close to an area of high circulation so that heated water can be rapidly and evenly distributed throughout the tank. This is usually near the filter system, the filter input from an external filter, or the airstones. The fully submersible heater should be placed at the bottom of the tank so that heating convection can be optimized. The sump is also a great place, because water is always moving through it.
