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Self-Improvement & Hobbies

Want to change pH?

Read up on the importance of pH stability and how to alter pH for your aquarium
CATS Classified In The Straits Times - October 16, 2010
By: Wong Wei Chen
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Want to change pH?

Suppose that you keep a vibrant red Siamese fighting fish in a spiffily decorated one-foot tank (and not in a jam jar, I hope). If you have done some homework, you’ll know that the Siamese fighting fish thrives in water with pH readings that are approximately between 6.8 and 7.2.

One day, you measure the pH level of your aquarium water, and obtain a reading of 7.4. That’s a little higher than the optimal range. So what do you do? Lower the pH, right? That would be the most obvious remedy, but given the complexities of water chemistry, altering pH is not as straightforward as it might seem.

Stable pH more important
While it’s important to keep pH levels within a range optimal for the species you’re keeping, pH stability is just as important, if not more so. Although 7.0 may be ideal for a certain fish, this critter will probably also do well with stable levels ranging between 6.8 and 7.2.

Within reasonable limits, pH stability comes to the fore as the key factor which determines whether fish will live or die, thrive or flounder. As we saw last week, a one-point change either way on the pH scale means 10 times more acidity or alkalinity. Sudden pH swings thus entail drastic changes in water chemistry, which could create considerable stress for your fish.

A constant pH that deviates slightly from the ideal range is better than a pH that vacillates between the upper and lower limits of the range.

But what do you do when you really need to change the pH? Before we go into the nuts and bolts, we need to get some background knowledge on buffering capacity.

Also known as buffering capacity, KH is a measure of the water’s ability to retain a stable pH despite the introduction of acids or alkalis. Buffering capacity is directly correlated with the amount of dissolved salts and minerals in the water. The more dissolved substances in the water, the higher its buffering capacity, and vice versa.

Occasions when pH change is required
On occasion, you may be required to alter the water chemistry. Some fish need a certain pH range to breed successfully, while more demanding plants require specific pH values to thrive. If you really must alter the pH, here are some pointers:

Increasing pH
This is usually easier than lowering the pH, and usually involves raising the water hardness at the same time to keep the pH stable. You can opt for one or more of the following methods:

    Use of decorations such as limestone rock, or stuff containing buffering salts

    Putting crushed coral in your filter

    Using commercial pH-raising products

Lowering pH

More difficult, but not impossible – just more troublesome if the water has good buffering capacity. Inexperienced hobbyists may resort to commercially available pH lowering reagents. These will work – but only temporarily. If your aquarium water has high buffering capacity, it will raise the pH back to the original level within one or two days. This pH swing will stress your fish, and you’re better off not changing the pH in the first place.

To lower pH and keep it there, you must first reduce the water’s buffering capacity. One way to do this is to purify your water using filters which are readily available in stores. Once dissolved salts and minerals are removed, your task becomes easier.

Another method is to bubble carbon dioxide (CO2) through the tank. As the CO2 dissolves, carbonic acid is formed, which in turn lowers the pH. However, for this method to work effectively, a continual source of CO2 is required; once the CO2 is gone, the pH will bounce back to its original level.


Water hardness

Decrypting pH