How To Monitor Water Quality – Part 2

In the previous article, we discussed the nitrogen cycle and how it affects aquarium water quality. Here, we shall elaborate on other water quality parameters that also matters.

The Right pH Level

pH is a measure of acidity or alkalinity. It is expressed on a scale of 0 to 14, with 7 being neutral- that is, neither acidic nor alkaline. The numbers refer to the concentration of hydrogen. The numbers refer to the concentration of hydrogen ions present.

Water is made up of hydrogen ions (H+) and hydroxyl ion (OH-), hence the formula for water being h2o. water naturally dissociates into H+ and OH- ions. If more H+ are present, the water becomes acidic (pH 0 - <7). If there are more OH-, the water is alkaline (pH>7 – 14). If they are present in equal numbers, the pH is 7 (neutral).

The pH scale is logarithmic, meaning that for every increase or decrease of one unit, there is a ten-fold change in the concentration of hydrogen ions. Therefore, even seemingly small changes in pH can have large effects.

Different species of fish evolved in habitats which differ in pH levels. For example, the pH level of the Blackwaters of the Amazon is around 6.0 or lower, whilst Lake Tanganyika in Africa has a pH of 8.5 to 9.0. Most species come from waters with pH level somewhere in the range of 6.5 to 8.5.

If you intend to keep sensitive or wild-caught species, or breed fish, you will need to provide an environment with natural pH. However, the majority of aquarium species are farm-raised, and less sensitive to pH than their wild counterparts. For these fish, the golden rule is to keep the pH stable, within the range of 6.5 to 8.5.

Fluctuation in pH often cause far more damage than the pH level itself.

pH level stability is affected by a range of factors such as the “buffering” capacity of the water (its ability to resist changes in pH), stocking levels, plant growth, feeding rates and so on. The only way of telling if the pH is stable is by testing the water. Failure to identify fluctuating pH can lead to fish stress, and eventually ill health.

Testing pH Levels

When you set up an aquarium, you should check the pH to ensure it is within the safe range for the fish you wish to keep. Once the aquarium becomes more heavily stocked, pH fluctuation is more likely to occur.

In a mature aquarium, the pH should be checked every one to two weeks. Check first thing in the morning before turning the lights on, and again towards the end of the day before turning the lights off. This is important because the process of photosynthesis by plant and algae during the day can affect pH.

If the pH level is fluctuating by more than 0.5 units during the testing period, seek advice on how to stabilize it. This may involve checking plant and algae growth, or increasing the buffering capacity of the water.

Other Water Quality Parameters

These include oxygen and mineral content. Ensure that the water is always well-aerated to maintain an adequate supply of oxygen. The mineral content is closely linked to pH levels, and is especially important for sensitive fish such as discuss. As you become more experienced at fish keeping, it will be worth your to include tests for these parameters.

For a start, concentrate on the four key parameters: ammonia, nitrite, nitrate, and pH. By checking these regularly, you will be rewarded with happier and healthier fish.

Source: Rupert Bridges, Tetra Information Centre

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