When it comes to tropical fish, the pH level of the water has a significant part in deciding whether your pets will be swimming around happily or floating belly up with a look of horror etched between their big bubbly eyes. A heightened pH is one of the leading causes of fish death in the home aquarium and is usually an easy fix, but ignoring one of them can be costly--and, if you really love your fish, traumatizing.
The pH level of a tank’s water is a measure of its acidity. Neutral water, like the kind you usually get in plastic bottles, is 7.0, which is the area most freshwater tropical fish tolerate fairly well. Fluctuations in pH can kill your fish, and therefore it is generally far more important to maintain a constant pH of between 6.5 to 7.5 instead of aiming for 7.0; fish are surprisingly adaptable. Having too high of a pH can be quite a hindrance and, unless you have saltwater fish, will probably result in some teary toilet flushing when your fish pass on. Though there are dozens of possible causes for a high pH, below are the two most common and their remedies.
Too Much Water Changing
Changing a percentage of the water is an essential part of maintaining a healthy tank environment, but too much of a good thing can be a bad thing, especially if you’re using tap water to refill the tank. Tap water is usually of higher pH due to the various metals and minerals it acquires through plumbing, and this, in turn, can cause a spike in your tank water’s pH level. Using bottled water or pre-conditioned water will do the trick.
Substrate is the lining at the bottom of the tank and is most commonly gravel. Certain types of limestone or lace rock can contribute to raising the pH, but the worst offender is crushed coral or seashells. Instead of these, use normal, natural gravel of rounded stones. Seashells and crushed coral are intended more for saltwater aquariums, which usually maintain a pH of well over 8.0.
If nothing works, there are chemicals available at any retailer designed to raise or lower the pH as designated. But be careful with these, for, as mentioned earlier, sudden pH fluctuations of pH can be just as damaging, if not more so, than a heightened pH in the first place.
Having a filter far too powerful will over-oxygenate the water, which drives down the carbon dioxide level, which in turn raises the pH. Make sure you have a filter big enough for your tank, but not so much that it contributes to killing off your fish.
If you can't afford bottled water (and most people can't afford gallons of it all the time), use a water purifier filter for your tap. This will not only ensure a proper pH, but keep out other harmful chemicals like chlorine, which, will actually kill your fish and not just make your eyes burn.