pH - What you can learn from it.

I remember back when I first started my venture into aquariums....I had done a lot of research, and I was determined to do things right. Luckily I got off on the right foot, but I didn't know everything. One of the more useful tools that we have as aquarists to check the quality of our aquairums is chemical testing. When I say this, I imagine that most of you first think of ammonia, nitrite, and nitrate. It is true that these are important compounds to keep track of in your aquarium, but once established, aquariums should have no trace of ammonia and nitrite. So what can you measure? The answer is pH. When I first started keeping aquariums, I had no idea what factors affected pH. I simply know that you wanted to maintain a pH between 8.1 and 8.3. Well, as it turns out, pH is important, and it can really help you keep a healthy aquarium.

pH is basically a measure of the ratio of the concentration of hydrogen ions [H+] to hydroxyl ions [OH-]. I am not going to bore you with another lesson in Chemistry...however, there are some concepts that you should know. First, pH is measured on a scale of 1 to 14. A pH of 7 is considered nuetral. A pH below 7 indicates a slightly acidic water, while a pH above 7 indicates a basic water. The further towards 1 or 14 you go, the more stongly acidic or basic the water. By now you may have noticed that the preferred pH of an aquarium is slightly basic (pH ~ 8.2).

Let's consider, for example, seawater. The pH of seawater is dictated by the concentration of carbon dioxide, CO2, in the water. This is because CO2 decomposes into carbonic acid, giving rise to a decrease in the water pH. This carbonic acid has the ability to decompose into carbonate and bicarbonate. Before you get frustrated with all of the chemical names I have just rambled out, let me sum this up into one basic point - mother nature regulates the pH of seawater by adjusting the balance between cabonic acid and carbonates. Basically this is the natural buffering system of the ocean.

So how can you apply this knowledge to your aquarium? Well the key is to understand what factors will cause the pH of your aquarium to rise or drop below the desired pH of about 8.2. Most of the time, pH will not rise in an aquarium. If it does, usually it will fall back to normal values soon after, and causes no major problems. Extensive lighting can cause such an event. The only time that this can be a problem is when one has inadequate filtration in their system. In the presence of poor filtration, increased pH can lead to increases in ammonia concentration in the aquarium, which is toxic to fish.

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