should be self explaintary..
pH is a measure of the acidity or alkalinity of the water, or in other words, the availability or unavailability of Hydrogen ions. What does this mean for your fish? Well, African Cichlids enjoy alkaline water conditions (i.e., pH above 7.0). pH levels vary depending upon the lake. The ranges for the three East African lakes are as follows:
Lake Malawi..................7.4 - 8.6
Lake Tanganyika............7.8 - 9.0
Lake Victoria.................7.2 - 8.6
These values are approximate ranges. In nature, the pH levels will vary somewhat as the levels of the lakes will rise and fall through the years, making them either less salty or more salty. In the aquarium, African cichlids can adapt to wide ranges of pH. What you need to be mindful of is to not make any rapid adjustments to the pH level. Such a careless or unknowing act will severely shock your fish, suppressing their immune system, making them more susceptible to disease. Keeping in mind all that I have said, I recommend keeping African Cichlids at a stable pH of 8.2 - 8.4. Fish from all three appreciate pH levels within this range. Cichlids from West African or the rivers and streams of East African require water that is more neutral - pH 7.0.
The water from these lakes is very hard, containing many dissolved minerals and salts, such as Carbonate and Magnesium. If you live in an area with hard water, you may count yourself very lucky. But for those who do not, there are many easy measures you may take to make your water more alkaline and "hard." Crushed coral sand, shells, limestone, and other rocks such as slate are good at pushing the pH of the water up into the alkaline range by adding Phosphates and Calcium to the water. These alone will typically only drive the pH to 7.6, which is suitable, but not ideal. Remember that Africans can adapt to a wide range of alkaline levels. If after using these measures, you still want to raise your pH, there are many commercial Cichlid buffers on the market. Several manufacturers also offer Cichlid Salts and Trace Elements, which try to simulate the exact salt and mineral conditions of the rift lakes, in addition to raising the pH.