Water Treatment
by Shelie Wittig ( Fishgal )

I can’t count the number of times someone has admired my aquarium and muttered something like, “We had fish once, but they all died.” This seems to be the result, more often than not, when beginners dive into fish keeping haphazardly. While you don’t need to be a rocket scientist, successful fish keeping requires some basic knowledge about water conditions, the nitrogen cycle and the specific needs of the fish you want to keep. So let’s start at the beginning, with the water.

There are really three basic steps to optimum water quality:

  • Remove any potential toxins from water before putting it in the aquarium.

  • Further condition it to simulate the precise chemistry best for your fish.

  • Maintain high water quality with proper aquarium maintenance.

This article will deal with the first step. And to address that, we need to consider where your water comes from and what danger it may pose to your fish.

Municipal Tap Water

If your water comes from a local utility, the most common problem is the likely presence of chlorine and/or ammonia – both of which are extremely harmful to fish.

Chlorine is usually added to the public water supply to destroy harmful bacteria and make it safe to drink. Unfortunately, in high concentrations it is toxic to fish, and even in lower concentrations it causes gill damage and consequent stress. Chlorine is easily removed with a de-chlorinating product (such as NovAqua®) or will dissipate on its own if the water sits in a bucket or tank (with some added circulation, such as an airstone or powerhead) for about 24 hours. NovAqua® also detoxifies copper and other heavy metals while adding to the fishes’ protective slime coating, so it offers many benefits.

Because of the fact that chlorine escapes to the atmosphere naturally, many water companies have taken to adding ammonia as well as chlorine, which creates chloramines. A de-chlorinator alone will only neutralize the chlorine, leaving deadly ammonia behind to stress and potentially kill fish before your biological filter eventually converts it to nitrite and then nitrate in your aquarium. Use of an additional product (such as AmQuel®) to remove ammonia will eliminate that danger.

Some municipalities add pH-raising chemicals such as sodium hydroxide, because high alkaline water is less corrosive to lead solder and copper plumbing. For African Cichlid enthusiasts, higher pH right out of the tap is a bonus!

If you live in the United States, you are fortunate to have fairly easy access to detailed information about your tap water. I tested this theory by calling my local utility to speak directly to a “water quality person” or “water chemist.” This man not only returned my call promptly, he spent a good 20 minutes answering questions and educating me. I learned that my tap water comes from two different sources, depending on supply and time of year. One source adds ammonia; the other does not. The moral of the story being that had I simply tested my tap water once and assumed to know what I was dealing with, I would have been wrong. Luckily, I have always taken the “better safe than sorry” approach and used products to remove chlorine, ammonia and chloramines. Do not be fooled by any product that simply claims to make tap water “safe”. Find out what harmful chemicals may be in your water and use products that specifically guarantee to remove or neutralize them.

In talking with the utility, you can also ask about pH, GH and KH (addressed in "Practical Water Chemistry") and if you really want details you can ask them to send you a copy of the water quality report they generate for the EPA. This could provide additional useful information such as indications of high phosphate levels, which are linked to algae problems. By law, the report should be available for public inspection.

Well Water

If your water supply comes from a well and you keep Africans, you may consider yourself fortunate. Not only is water from deep, drilled wells considered by many to be superior in quality, it is likely to have a higher mineral content and consequently test higher for hardness (although many households use a “water softener” to remove dissolved minerals), it may have a higher pH, and there should not be any chlorine or ammonia present.

Wells tap into the groundwater supply, which is naturally filtered through layers of sand and rock and is not polluted as easily as lakes and rivers (particularly in very deep wells). There are however, a few considerations you should be aware of.

  • Well water may contain nitrate, especially in agricultural areas, due to the use of nitrogen fertilizer. Since nitrate is a natural byproduct of the nitrogen cycle in your aquarium and is typically removed with water changes – you may need to seek other methods to reduce nitrate in your aquarium. The deeper the well, the less likely this is to be a problem.

  • Well water often contains high concentrations of dissolved gases such as CO2, which lowers pH. If the water is aerated for a few hours before adding it to your aquarium, harmful gases will escape and your fish need not be subjected to temporary pH fluctuation or other stress.

  • Lastly, there is the concern of shallow wells being polluted or contaminated, often by nearby septic systems. If you question the quality of your well water, it may be worth the minor expense to have a sample professionally analyzed.

Additionally, the only way to determine all the properties of your well water (aside from having a sample analyzed by an outside source) is to run tests on it yourself using a proper aquarium or pond water test kit.


Regardless of where your water comes from, if you hope to raise healthy, beautiful fish you should learn about it and treat it accordingly before putting it in your aquarium. What looks crystal clear coming out of the tap, isn’t necessarily safe for your fish. □


Advertise with us

  (©) Malawi Mayhem 2014.   Site design and web hosting by NameSonic.com.  
Proudly Canadian