If you own an aquarium, the pH level of the water is one of the crucial aspects of the health of your tank. pH needs to be monitored regularly—even in established aquariums, various factors could cause the pH to shift in a fairly short period of time.
First, some basics. The pH scale is used to measure the acidity or alkalinity of a substance (in this case, aquarium water). The scale goes from 1-14, with 7 being the happy medium: neither acidic, nor alkaline. From there, any number below 7 is a measure of acidity, with 1 being the most acidic, and any number above 7 is a measure of alkalinity, with 14 being the most alkaline. Pure water is usually very close to a 7 on the pH scale.
One very important thing to note is that the pH scale is logarithmic. A pH of 6 is 10 times more acidic than a pH of 7, and a pH of 5 is 100 times more acidic than a pH of 7. That means a difference of one number, which may not look huge, is actually very significant for the inhabitants of your aquarium.
The pH of your tank could change for a variety of reasons. The change could be caused by you, for example, with the addition of any fluids or solids to the aquarium. Or, it could result from the natural processes occurring inside the tank. For instance, excess carbon dioxide from fish respiration, if not dealt with, can result in acidification of the water in your tank.
So what’s the right pH for your aquarium? That depends, though most aquariums tend to thrive very close to the neutral range (a pH of 7) for freshwater aquariums, and more alkaline (a pH of 8.2) for saltwater. Consult your aquarium technician during the setup phase of your aquarium, and he or she will be able to tell you what pH number to stick to. From there, it’s a matter of testing frequently enough.
While aquarium inhabitants do have some tolerance to pH fluctuation, you’ll likely want to keep the pH very closely to the recommended number. A change of more than .3 within a 24 hour period is considered significant, and can be stressful to the fish population of your aquarium.
The testing can happen in a variety of ways, from low-tech pH strips to full-time digital meters. Ask your service technician what testing method he or she recommends for your specific aquarium setup.