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Home > Articles > Questions on Water Temperature for saltwater tanks

Tuesday, 22 November 2011

Questions on Water Temperature for saltwater tanks


What temperature should it be?
• I prefer my reef tank around 24’C-25`C.
• Most hydrometers are most effective at 25`C.

What is the lowest temperature that is still safe?
22’C is fine for most corals and fish.

What is the highest temperature that is still safe?
27’C is fine for most corals and fish.
(Higher temperature speeds up the metabolism and makes organisms grow faster).

What happens if the temperature gets too high?
This is a common and major problem in a marine aquarium.
• The first thing to remember about temperature is that it is not only the temperature itself that affects the fish and inverts, it’s also a series of chemical reactions to the increased heat and temperature fluctuation.
• Saltwater fish and inverts are unable to cope with fluctuations such as a tank being hot one day and much cooler the next.

High temperatures create a series of problems.
• The high temperatures lower the oxygen levels in the aquarium and make it harder for the fish to breathe.
• The absence of a surface skimmer can create a build-up of gases or chemicals on the top of the water surface that can insulate the heat and hamper the tank’s ability to defuse carbon dioxide.
• The temperature fluctuation can also stress the fish, making them breathe quicker and therefore need more oxygen that may not be available. The less oxygen available, the more the fish stress, and the more oxygen they need.
• The heat will make any organic waste you may have in the aquarium more toxic.

What should I do when my tank gets too hot?
• A simple attempt to lower the temperature is to add an air-stone. This ensures the surface is rapidly broken so heat is able to diffuse out of the tank. It also increases the availability of oxygen. When the temperature increases the fish can stress, causing them to gasp. If there is not enough oxygen in the tank to cope with the increased gasping, the fish will stress more, in turn requiring more oxygen so the situation becomes worse.
• On a hot day, point a fan at the tank to cool the surrounding air.
• It can help to take off the lids to add heat diffusion, but beware of doing this if you have fish that are known for jumping out such as eels.
• The ultimate way to lower temperature is to get a chiller unit which is pricey but worth it.
• You could look at air conditioning the room, this way you will be cool as well as the tank.
• Never turn off the heater. The heater won`t come on if the temperature is above what it is set for, though in the event of sudden colder weather it will maintain the temperature.
• Placing water in a bottle and freezing it, then floating it in the aquarium or sump is one of the most obvious things people do. I rarely suggest this because it isn’t prevention, it is a temporary cure. If you are forced to do this I suggest you search for a more consistent method because you will not always be home when it is hot.
• You can also make your own chiller using a second hand bar fridge or a camping freezer. The way to do this is to run some flexible pipe trough the freezer compartment that is pumped from and returned to the tank or sump. Ensure that the heater is more powerful then what the freezer is set for so the tank is not able to go below what the heater is set for.
• Ensure your organic waste is down and the water chemistry is correct for the fish you are keeping. The presence of the waste or incorrect chemistry will further stress the fish. (Some toxins become more toxic when the temperature is increased).
• For a situation with a built-up reef, the shelves help to lower the amount of organic waste that accumulates in the back of the aquarium. The presence of the gases, chemicals and stagnant water may add to retaining the heat.
• If there has been a problem with the water temperature e.g. it has had a cold or hot flush, don’t feed the tank for a day or two because unseen damage may have been done to the biological capacity of the tank. The absence of food can make or break this situation.
• If the heat is a problem you may have to get better quality powerheads that don’t generate as much heat.
• Try to avoid cabinets with closed backs because the heat will accumulate.

What happens if the tank gets too cold?
• If the water gets too cold the fish tend to become prone to disease and stress.
• You obviously turn the heater up if the tank is too cold.
• It is smart to have a spare heater because if one dies you have one on hand instead of having to race down to your local aquarium store in a panic.

By Paul Talbot


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