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AQUARIUM PH : TO BE OR NOT TO BE CONSIDERED?
By Madhu Soodhanan of India
Whenever one surfs the net or refers to a book about fish-keeping, pH would be a short-listed,
important point of concern. Many of us have read articles/books saying fishes are not tolerant
to wide pH ranges or pH fluctuations. But is pH that important in fish-keeping? Is it easy to
What is pH?
pH is a logarithmic scale of the proportion of H+(Hydrogen) and OH-(Hydroxyl) ions ranging
from 0-14, with a neutral value of 7. When the H+ ion concentration is higher, water is said to
be acidic; when OH- concentration is higher it is said to be alkaline. In other words if the
concentration of dissolved minerals is high then pH is high and vice versa. pH is also dependent
on various factors like water hardness, dissolved minerals, oxygen level and many more.
Many believe that even the smallest change in pH is highly stressful to aquarium fish. You might
have come across volumes saying that a pH of 6.5 is 10 times more acidic than a pH of 6.6.
Many have a deep rooted feeling that all fishes in the wild live in perfectly stable and narrow pH
ranges and fishes cannot adapt to changes in pH, and some say that fishes will perish
immediately in case of any pH changes.
What happens actually?
In the wild, pH is not as stable as many of us think. It fluctuates considerably. In Indian waters I
have observed higher pH during day times and lower during nights. Also, pH is lower in autumn
and higher in spring. In autumn, dead leaves fall and decay in watersheds leaching out acids like
tannin, which acidifies the water. In spring there are more monsoon rains, hence more oxygen
dissolves and therefore the pH pumps up.
In aquaria, pH is not perfectly stable either. pH changes in accordance with aeration,
decoration, gravel, temperature, nitrate content, dissolved minerals and many more.
? Aerating 20 liters of water for 4 hours took my tap water pH from 7.8 to 8.6.
? Gravel that you use also plays an important part in your tank's pH. Any decor like corals or
fossils hikes your tank's hardness and hence your tank's pH.
Decorations like driftwood or bogwood can lower pH.
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