Water changes are an essential part of any well maintained aquarium, as they help maintain tank stability. The frequency and amount of water changed is something that every hobbyist is constantly trying to balance. Those who have recently entered the hobby rarely understand why or how water changes should be conducted. This article will explore everything you need to know about water changes. Whether you are a beginner or a seasoned aquarist this article should have something for you to learn.
How often should I change the water? This is a common question asked by many in the hobby. How often you change the aquarium water is largely dependent on a number of factors, including; the amount of water being changed, the number of fish in the aquarium, the type of fish in the aquarium, the water chemistry and the presence or absence of plants in the aquarium.
Amount of Water Changed
The frequency of the water changes and the amount of water changed are closely linked and need to be considered together. The “less water changed, the more frequently the water should be changed” is a general rule used in the aquarium hobby. While this rule can be followed, it should not be used as a ‘be all and end all’ solution to water changes because the opposite of this rule is not necessarily true, that is; ‘the more water changed, the less often water changes need to be conducted’. This is absolutely false. Fish, like humans, become accustomed to routine and when water changes are not conducted on a regular and routine basis, they can cause significant fish stress when they are conducted. For example, if your normal routine is to change 10% of the water every two weeks and then, for whatever reason, you change 50% of the water, this would cause your fish to become stressed. Having said that, during disease or an ammonia spike, large water changes can be conducted, even if that is not your normal practice. Under those circumstances the water change will cause less stress than the disease or ammonia spike and is therefore, the lesser of two evils. The best and easiest way to solve an ammonia issue in the aquarium is water changes. The sooner the ammonia level is brought to zero, the less problems the aquarist will encounter.
Number of Fish in the Aquarium
The number of fish in aquarium is often referred to as the ‘bio-load’. The ‘bio-load’ refers to the amount of waste produced by the fish rather than the actually number of fish. This is due to the fact that different species of fish produce different amounts of waste. Larger fish will produce more waste than smaller fish. However, certain species of fish also produce more waste than their counterparts. Sucking catfish (i.e. Plecostomus, Ancistrus etc.) are a classic example, as they produce large amounts of waste in comparison to other similar sized fish. The frequency of feeding and the amount you feed your fish is also a contributing factor. The more you feed your fish, the more waste they will produce and subsequently the more water changes you will need to perform. Fish can survive on surprisingly little food. Most fish only need to be fed once a day and then, only as much as they can eat in a couple of minutes.
Plants or No Plants
Aquarium plants are able to absorb the products of fish waste as nutrients and thus, aid in the establishment of a balanced and healthy system. Heavily planted tanks have the advantage of requiring fewer water changes, as the plants are able to deal with the fish waste. However, there are exceptions. So called, ‘hi-tech’ tanks often require weekly and large water changes. The reason for this being that the nutrients which are artificially added to these aquariums in the form of liquid fertilisers, tend to build up over time. Hobbyists who maintain ‘hi-tech’ planted tanks often opt to conduct frequent and large water changes as a way of controlling nutrient levels. The water changes prevent the build-up of nutrients and bring the tank back to a ‘base nutrient level’ at the end of each week. So called, ‘low-tech’ planted tanks seldom require water changes on this scale. It is true that a well thought-out ‘low-tech’ tank can be maintained with next to no water changes and some hobbyists have even removed their filters from such tanks, as the plants alone are able to keep the tank healthy. However, unless you have a good deal of experience with such set-ups, I would not recommend trying this. It is important to note that most hobbyists who have removed a filter from one of their tanks, have removed it from a well-established setup. Such tanks rarely experience changes in water parameters and are not as prone to ammonia spikes, disease and fish deaths. Removing a filter should never be attempted on anything other than a heavily planted tank.
Water Parameters and Water Changes
Another consideration when conducting water changes is the parameters of the aquarium water. Hobbyists who maintain their aquarium’s parameters at the same levels as those in their tap water need not pay too much attention to water parameters. When the aquarium’s parameters match those of the source water, water changes aid in maintaining stable conditions. However, if this is not the case, and the aquarium’s parameters differ to those of the source water, then water changes can rapidly alter the parameters of the aquarium water and cause significant fish stress. It is always advisable to choose fish which require water parameters similar to those of your source water, as artificially altering your aquarium’s water parameters to satisfy the inhabitants will always pose a risk.
The difference between the temperature of your aquarium and the temperature of the source water is also an important consideration to make, as sudden changes in water temperature can cause temperature shock in fish and can even result in death. For this reason, if your source water is significantly colder than the water in your aquarium, it would be advisable to heat the source water before adding it to your aquarium. For freshwater hobbyists, this is fairly straightforward. Simply use water from both the cold and hot water taps to create warmer water. The water does not have to match the temperature of your aquarium exactly, however, it is important to raise the temperature to within 2-3 degrees’ difference of your aquarium.