Monday, January 6, 2014

Dealing with Toxic Effects of Chlorine and Chloramine



Dealing with Toxic Effects of Chlorine and Chloramine


Both saltwater fish and freshwater fish are affected by chlorine and chloramines. Chlorine is classified as an oxidizer and can burn fishes’ gills. On the other hand, Chloramines pass across the gills and into the blood where the molecule attaches to the hemoglobin to induce methemoglobinemia. The fish then suffer from anoxia, a condition which is characterized by low levels of oxygen in the tissues. This is associated with the conversion of hemoglobin to methemoglobin. Hemoglobin functions as a carrier of oxygen in the blood. Fish suffering from chloramines poisoning appear to respire heavily and are sluggish.



The degree of toxicity induced by chloramines is mainly influenced by water pH, with chloramines being more toxic at lower pH.

At high concentrations, chlorine can be toxic to fish. Concentrations as low as 0.2-0.3 ppm can kill fish fairly rapidly. At lower concentrations, chlorine can cause stress and damage the gills of fish. To prevent stress, chlorine concentrations should be as low as 0.003 ppm.

There are many aquarists that perform partial water changes without applying any type of water treatment or water conditioner to remove chlorine. Fish in untreated water may appear to be apparently healthy but that doesn’t mean it is not being subjected to stress as a result of the presence of chlorine. The stress level depends on the amount of chlorine present in the aquarium tank, which, in turn depends on many factors including the percentage of new water which is added to a partial water change.

When chloramines are eliminated with the use of specific chemicals, ammonia is released and can pose harm to fish, even if fish normally produce some ammonia as a natural by-product of metabolism. Ammonia levels may be acceptable however there are commercial products which can remove excess ammonia in ponds and fish tanks. Biological filters, pH control adjuster methods, and natural zeolites are also beneficial in reducing the harmful effects of ammonia.

On the other hand, chloramine poses two important challenges for aquarists. First, using sodium thiosulfate can only neutralize the chlorine part of chloramine, which, can lead to an even bigger challenge: the generation of deadly ammonia. A tank’s biological filter will eventually convert ammonia to nitrate however the time element is quite long—longer than what your fish population can tolerate.

The second challenge relates to the water changes. One of the main objectives of regular water changes is to eliminate the build-up of nitrate. If ammonia is present in your replacement tap water, you will be putting back nitrogen into your tank thus making it impossible to lower the nitrate level. Fortunately, most tap water have relatively low concentrations of nitrate (1-2 ppm) compared to your tank.

Chloramine can be safely neutralized in several ways:
  • Use of products such as API Ammo-Lock which can neutralize both ammonia and chlorine portions of the chloramine molecules. The ammonia which will be neutralized will be converted to nitrates by the tank’s biological filter. 
  • Ageing chloramines while simultaneously undergoing biological filtration. This is achieved by filling a container with tap water and adding sodium thiosulfate to dechlorinate it and then connecting to an established biological filter which will convert the ammonia to nitrate. The purpose of adding sodium thiosulfate to the water is to neutralize the chlorine otherwise, the chloramine can kill the population of beneficial bacteria in your biological filter. 
  • Filtering the water through carbon or zeolite before adding to your fish tank can remove ammonia. 

Useful test kits to get


Some of the test kits that are most useful include the following:

Ammonia test kit


An ammonia test kit can help determine ammonia levels in your tank. This is useful because it can help determine when the nitrogen cycle has been completed in a tank-cycling phase. Second, an ammonia test can verify whether your biological filter is working or not especially when there are unexplained fish deaths. Even if you feel you have an established tank, your biological filter can sometimes weaken or outright fail.

Nitrite test kit


Just like ammonia test kits, nitrite test kits are useful in the same circumstances however it can further provide information regarding the completion of the second phase of the nitrogen cycle.

Nitrate test kit


Over time, the levels of nitrate in established tanks can rise as an end result of the nitrogen cycle. This is often the case except when your tank is heavily planted, when plants are able to consume nitrogen faster than it is produced. Since nitrates are toxic at high concentrations, they should be regularly removed through regular water changes.

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