[Myka]

pH is the most misunderstood parameter. Don't try to adjust the pH with chemical and additives, all that will accomplish is a short term change, and the pH will drift right back to where it was. Next thing you know alkalinity will be up at 15 dKH and you're still wondering why your pH is low. You can very easily have high alkalinity and low pH. Alkalinity does not directly affect pH.

With your tank being so new, it is not a surprise at all as it takes several months for a tank to settle in. How big is your tank? Are you using a protein skimmer?

the two most common causes of low pH are an inability to off-gas CO2 because either you aren't using a skimmer or your house isn't getting fresh air (can't get rid of CO2 if the skimmer is sucking in CO2), and high bioload (fish poop is acidic).