I do not know what they have in this buffer, I did not see a list of ingredients unfortunately.
What do the products sold as buffers for the purpose of increasing pH have in them?
Many will have the equivalent of baked baking soda (soda ash or sodium carbonate). The pH of sodium carbonate is higher than that of regular baking soda (sodium bicarbonate). When supplementing for alkalinity with the sodium carbonate it will results in higher pH levels.
Some products will have a combination of baking soda and baked baking soda, which will result in not as much a pH increase. In between the two so to speak.
Other products will add borate to the above two possibilities. The borate will result in higher pH levels, but will mess with your alkalinity kits and produce deceiving results if the borate content is too high.
All of these buffering products should be dosed to maintain your alkalinity or you will end up with high alkalinity levels.
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Your current pH is fine and you do not need to worry about it, unless your pH drops below 7.8. Many Reef of the Month tanks run their pH at your current level.
Randy goes into more detail regarding low pH problems in this article:
Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm