One key to having success in the marine aquarium hobby is stability within the aquarium, including a stable temperature. There are many factors that can cause temperature changes in the tank and just as many ways to help control these. This article will address the three major contributors that cause the heating of the water in your aquarium and then discuss some options for cooling the aquarium itself.
Causes of heat in the aquarium
Pumps
Reef tanks and marine tanks alike both need good water movement/circulation for the inhabitants to be healthy. To provide this water movement in the aquarium pumps and powerheads are used, either internally or externally. Both internal (submerged) and external pumps can add heat to the water as a means of cooling themselves. Different pumps will add different amounts of heat to the water. With a little research, you will be able to find out which pumps cause the least and the most amount of heat transfer to the water and can choose a pump that works best for your system.
Lights
Corals in a reef tank require high intensity lighting to survive. These high intensity lighting fixtures will become another major heat producer. It will not matter whether you are using VHO, PC, T5 or metal halide lighting. All these lights will produce heat that can affect the water temperature in your tank especially when enclosed within a canopy.
Room temperature
Room temperature will also have a large affect on the temperature of the aquarium. This may seem obvious to some people, but the higher the room temperature is the higher the temperature of the water in the tank will be. Summer time is usually the worse time of year when dealing with room temperature problems, but even spring and fall can have their share of extremely warm temperatures. If lucky enough to have central AC, this may not be an issue for your tank, but otherwise trying to put your tank in a room that generally stays cooler (i.e. doesn’t have the sun shinning in the room all day long).
Cooling options
As mentioned before, there are just as many methods for cooling a tank as there are causes for the warming of them. Some methods are very simple, while others are a little more complex. Depending on the size of the tank and the amount of temperature changed needed, you will need to choose what method will work best for your application.
Floating ice method
The floating ice method can be done many different ways, but one of the easiest methods is using empty two liter soda bottles (or smaller bottles for smaller aquariums). Fill the empty bottles with water and put them in the freezer, making sure there is enough room in the bottle for expansion of the water when it freezes. Then once the bottles are frozen, they can be placed in the sump or main tank to help chill the water. One of the advantages of this method is that it is very inexpensive to do. But there are many disadvantages to this method including you will need to change out the bottle through out the day to help maintain a stable temperature in the tank. Unless you are home 24/7 this may be impossible to accomplish. This is a very “hands on†method of tank cooling but not the most efficient cooling method.
Fans
The use of fans is another method for cooling that can be very useful. There are a couple of different methods that can be implemented alone or together. First is using fans to blow the hot air that is produced by lighting fixtures away from the tank. Although this can lead to increased room temperatures, it will at a minimum keep a major heat build up from occurring directly over the tank.
The second use of fans for cooling the aquarium is by blowing air across the water surface. By blowing air across the water surface it will cause an increase in evaporation in the tank. In turn the evaporation will help cool the water in the tank, called evaporative cooling. Depending on the room temperature and humidity, a fan can cool a tank by 2-4 degrees fairly quickly. If the room temperature is high and humidity levels are also high, this will dramatically affect the ability of evaporation to cool the tank. One obvious disadvantage to this cooling method is the amount of water that will need to be replaced on a daily basis. For larger tanks, this can easily amount to 3-5 gallons per day from evaporation. Some fans can also be loud, adding to the noise levels coming from the aquarium.
Chillers
Chillers are by far the best method of cooling an aquarium. Chillers are basically heat exchangers. Most chillers use titanium coils and a refrigerant to cool the water as it passes by the coils. There are two main types of chillers available on the market today, inline and drop-in. The inline chillers require water to be pumped through the unit. The cooling of the water will occur within the coils located inside the chiller. These chillers can be placed anywhere in relationship to the tank. For example the chiller can be placed outdoors (in a protected shelter), in a garage or in a different room as long as the user is able to pump water into the unit. The drop-in chillers have the titanium coils external to the actual unit. The coils need to be placed into the sump where water can pass by the coils to be cooled. The advantage to this type of a chiller is there is no plumbing needed, so it is very simple to install. One of the disadvantages of the unit is it needs to be placed right next to the sump as the coils and flexible refrigeration line coming from the chiller are normally around 3-5 feet long.
Whether the inline or drop-in chiller works best for you, it is important to allow plenty of ventilation around either unit. The chillers will give off heat while they are cooling the water. If the chiller is placed in a closed area, such as a closet or aquarium stand with out any opening, the unit will not be able to chill properly and could add extra heat to the tank.
Also it should be noted that chillers will require a temperature controller to function. Some units come with built in temperature controllers while others have external or remote controllers.
Controllers to help keep temperatures stable
What are temperature controllers and what can they do for your tank? As mentioned, chillers require a controller to function properly. A temperature controller will turn on and off a chiller or other equipment such as a fan at a given temperature setting. For example if you want your tank to get to a maximum temperature of 80 degrees F, you would set the controller to turn on the chiller when the temperature hits 80 degrees. The controller will turn on the chiller when the temperature gets above 80 degrees and then once the water has been cooled below 80 degrees it will automatically turn the chiller off.
There are two basic types of controllers available, a single stage and a dual stage. A single stage controller will turn on and off one piece of equipment, such as a chiller or a heater. A dual stage controller will turn on and off two pieces of equipment, such as a chiller and heater. For the most stable temperature control of your aquarium, the dual stage controllers are the best option. The dual stage controller will turn on the chiller when the tank gets too warm and will turn on your heater when the temperatures get too cold.
There are many factors that can be very difficult to control in a reef tank, temperature does not have to be one of them. Stability will help the overall healthy and well being of your tank. With the temperature staying within a controlled range, you are able to eliminate one factor that can put stress on your tanks inhabitants and hopefully lessen other stressors that can affect your tank.
