01/06/2019
Axolotls: Acidic or Basic/Alkaline?!?!
pH stands for "power of hydronium". Water (H2O) exists in a constant equilibrium with itself: H2O OH- + H+. The hydrogen ion (H+) is very small and strongly hydrated (meaning it attaches itself to another water molecule), essentially existing as the ion hydronium (H30+). pH is a convenient way of expressing the hydrogen ion concentration. In actual fact, it's the negative logarithm of the hydrogen ion concentration.
The pH scale ranges from 0 to 14. A solution (i.e. water containing something else) with a pH of less than 7, is said to be acidic. A pH greater than 7 is considered basic (also known as alkaline). And a pH of exactly 7 is considered neutral, neither acidic nor basic. The further the pH is from 7, the stronger the acidity or alkalinity/basicity of the solution. You can obtain simple-to-use pH test kits from your local aquarium retailer.
Most municipalities treat their water so that it is within a few degrees of pH 7 (neutral). My local water is 7.2 after treatment. For axolotls, a pH of 6.5 to around 8.0 is acceptable, but 7.4 to 7.6 is probably ideal. pH can affect the toxicity of ammonia and this is discussed below.
Ammonia, Nitrite, & Nitrate:
These three substances are part of the biological filtration cycle in your aquarium. Ammonia, NH3, the main waste product produced by your axolotls, is very toxic in its unionised form (NH3 as opposed to NH4+). A low pH means a higher concentration of H+ ions, which in turn results in a higher degree of ionisation of NH3 to NH4+. Conversely, a high pH means that unionised ammonia, toxic NH3, is the main form of ammonia. What this means in English is that the higher the pH, the more toxic the ammonia. Ammonia can kill, and at a pH of 8 or more, it kills even more effectively. Water temperature can also affect its toxicity, a higher temperature resulting in a higher toxicity.
Unless you're extremely proficient with maintaining aquarium systems, a periodic ammonia test is advisable. Even the most experienced hobbyist should occasionally test for ammonia.
Nitrite, NO2-, is produced from ammonia by the bacterium Nitrosomonas. It is not as toxic as ammonia, but should also be tested for regularly. Again, test kits are available and should be used about as regularly as ammonia tests.
There’s plenty of information out there on this topic, this is just one source, and as always I urge you to DO YOUR OWN RESEARCH as well. 🙃