Heat has an effect on all organisms including humans. Of course marine aquariums don’t have to be tropical, there are cold water seas as well. However, a guess suggests that most aquariums kept are tropical, fish only or reef. All aquariums, tropical or cold water, can be hit by heat which could be detrimental.
Tropical aquariums are heated to a known and pre-set level. Cold water ones are not but can also warm up in a detrimental way. With the onset of warm weather in many areas the aquarist needs to be on guard and ready to take protective action. Tropical marine fish and corals come from different areas of the world where the sea is a different temperature. What is perfect for one fish could be too cold or warm for another.
Absolutely the best way for an aquarist to proceed is to find out, from the dealer or on line, where an organism comes from. Then find out the temperature of the sea in that area. Then set the aquarium temperature to match. There can be considerable differences in sea temperatures governed by area. The problem here is that organisms are usually required that are free choice, that is, tropical area is not considered. In this case, the temperature is set to what is considered to be a safe point, this being 77deg F. This is considered too low by some who set the temperature to 79deg F.
All aquarists should monitor the temperature of their aquarium(s) whether the weather is warm or not. The best way to heat is with two heaters, each one half of the total wattage required. Though there could be a slight difference in the response of each heater, the difference doesn’t cause problems. Some opinion suggests a better way is to connect the heaters to an external heater controller. The external controller has a sensor that sits in the seawater. The controller is set to the required temperature and switches the heaters on and off as required. The temperature should of course be regularly checked using a fixed in place thermometer.
If seawater is permitted to overheat by lack of attention or suitable controls it isn’t just warmer. The amount of oxygen available decreases which of course could be a major problem, particularly with an aquarium that is heavily stocked with fish, this is one reason (there are others) why overstocking should be avoided, understocking is far better and the aquarium can look just as interesting. The general rule is 1″ of fish to 5 gallons of seawater (remember fish grow). Online there are methods of working out stocking levels which should be more accurate.
A danger of warmer than required seawater is that oxygen levels decrease. One major warning of this is when fish hover just below the surface where oxygen is at a higher level. This sometimes doesn’t happen so thermometer checks are the reliable way. Dissolved oxygen in seawater is about 20% less than in freshwater. Oxygen in the aquarium is dependant to a large extent on the surface area of the aquarium where oxygen intake occurs. More oxygen is taken in when there are weirs and the like. Circulation pumps help to move seawater to the surface. Hopefully the oxygen level will be close to or at saturation.
Overheating is dangerous to the fish and other organisms. If the temperature has risen to the required level and continues to rise, obviously the heaters should have switched off. In the small volume of seawater that is in the aquarium exterior temperature has a big effect. Controlling excessive temperature is generally easy. Consideration needs to be given to how often and how reliable high exterior temperatures are. Clearly in an area where summers (or longer) are always hot then a more permanent and more expensive system can be considered. In an area where hot periods are less likely then a simple system could be introduced. Both systems do not need to be permanently attached unless the hot weather is year long, of course.
The simple system that can control the seawater temperature to a reasonable degree is an electric fan. Some direct the fan across the seawater surface which is effective but does increase the evaporation, meaning the seawater level has to be more regularly checked. Remember, the salt does not evaporate only the water, so ordinary water, not seawater should be added as required. Alternatively, a desk type fan could be placed on the floor with the air flow directed as near as possible across the front glass of the aquarium, this causes the aquarium to act to an extent like a radiator.
The more expensive and powerful system for use where high external temperatures are common is the cooler unit. This is easily fitted. It’s a pump that circulates seawater through a cooler unit, a bit like a ‘fridge. The unit is controlled by a temperature sensor which avoids excessive cooling. Obviously the cooling should not go below the required temperature level or the heaters and cooling unit will battle each other.
It’s all very straightforward and doesn’t require large financial expenditures. The organisms in the aquarium appreciate a controlled temperature as their metabolism is directly affected. They will be healthier and live longer. The aquarium will be as beautiful and interesting as it is in the cooler days. Any equipment is easily obtained and fitted and, apart from more regular checks in warm/hot days, the aquarist has no more work to do.