I was wondering because my tap pH is 7.6 but it is never under 8 in my tanks. If it IS higher after 24 hrs. then you probably don't need the coral unless you are doing it for a specific reason, like you mentioned some Cichlids. If you do take some out do it slowly so you dont drop it too fast.
Do you have plants/algae?
"Because plants take inCO2during the day and release it during the night, pH levels in water can change from daytime to night. For an example of how pH typically varies over a daily cycle, select here. Acidic and alkaline compounds can be released into water from different types of rock and soil."
"pH varied significantly over 24 hours. These diurnal fluctuations in pH are controlled principally by rate of photosynthesis, rate of respiration, and buffering capacity. Photosynthesis rates are controlled by nutrient concentrations and availability of light. Respiration rates are influenced by availability of organic waste and temperature. The quality and dilution of effluent from the WWTP greatly influences diurnal changes in downstream pH.
During photosynthesis, aquatic plants remove carbon dioxide from water, which causes a rise in pH. During decomposition of organic matter, carbon dioxide is released as an end product. At night, when plants respire, they release carbon dioxide to the water, causing a decrease in pH.
Summer pH values show greater variation than winter pH values because there is more light and warmer temperatures, producing both higher community photosynthetic and respiration rates."