How to Buy the Right Aquarium Chiller

By Richard Gillillan

Whether you have a warm water reef setup, or you specialize in cold water marine species, an aquarium chiller is a great investment. The chiller allows you to raise a cold loving variety of marine species that requires cooler temperatures than you are willing to maintain in your home or office. For marine aquarium owners, an increase of water temperature can be a real problem, because the warmer saltwater holds less oxygen than cooler saltwater. If water warms up too much from sunlight or heat production caused by other aquarium equipment, the marine organisms can suffer due to a lack of oxygen.

What is an Aquarium Chiller?

An aquarium chiller is a piece of equipment located outside the aquarium that helps you maintain a constant temperature in your marine aquarium. Just as you have an aquarium heater to warm the water to optimum temperatures, especially on cloudy or wintry days, the chiller cools the water down, and keeps it from getting too hot. Other aquarium equipment, such as lighting and water pumps, actually release heat into the water, so the more equipment you have running, the more you might require the services of a chiller.

The chiller itself gives off a large amount of heat, and careful planning needs to be used to make sure the unit has plenty of ventilation. In fact, housing the chiller in an under-ventilated area, such as an aquarium cabinet, can lead to an increase in water temperature. Another aspect of chillers is that some chillers need to be plumbed into your aquarium system, so the sooner you decide to add one to your new aquarium setup, the easier it is to plan and build any necessary plumbing for it.

The Types of Aquarium Chillers Available

When purchasing an aquarium chiller, you have a choice between an in-line water chiller, a thermoelectric chiller, or a drop-in water chiller.

The in-line chiller is meant to fit onto a larger aquarium setup, and is usually used for saltwater aquariums. This chiller requires plumbing to make it fit into an in-line filtration system, which means that you should try to add it into your aquarium at the blueprint stage, before any part of your system is actually built. This chiller fits into the system where it can take already filtered water from the sump. The water runs across the chiller's coil, cools, and then is returned to an area in the sump just before the main return pump moves water into the aquarium. In-line chillers are available in a variety of sizes, from 1/5 to one horsepower.

The drop-in chiller is the simplest to install, because it consists of a coil which is placed in the sump of the aquarium or in the wet/dry filter. The coil is made of titanium and filled with refrigerant, and then sealed so it is waterproof. This coil is connected to the unit's compressor by a thermostat. Drop-in chiller sizes range from 1/5 to 1/3 horsepower. The drop-in chiller is used mainly by aquarists with saltwater reef aquariums. Because no plumbing is involved, the drop-in chiller works very well for systems that don't have lots of room for accessories.

Thermoelectric chillers use the idea that a current sent through two different conducting materials will heat up on one side, while the other side rejects heat. This chiller has the hot side insulated from the cool side, and the cool side is pointed towards the aquarium, which cools the water. Thermoelectric chillers should be used only on aquariums up to 15 gallons. These chillers are quiet, but they're also only effective on aquariums with slow water flow. Fast flow can overwhelm this chiller system.

What to Look for in a Good Aquarium Chiller

Before choosing the correct aquarium chiller for your setup, you need to consider a number of items. First, do your homework and discover the temperature comfort zones for your aquarium livestock. Some creatures and plants tolerate heat better than others. You also need to figure out the size of your total aquarium system, including the sump area, since a large system is going to need a bigger chiller. Also factor in the amount of equipment you use that gives off heat into your aquarium water.

If you have a saltwater aquarium, always purchase a chiller with a titanium heat exchanger, because copper exchangers exposed to saltwater can poison your livestock, and stainless steel corrodes over time. When deciding on the correct sized chiller for your aquarium, remember to invest in a chiller that is slightly larger than you require, because a larger chiller is going to do the job more efficiently, and will run less often. Chillers which are somewhat undersized tend to kick on and off more often, which makes them work harder and uses a much larger amount of electricity.