One thing to remember is that pH and alk are linked, but only as long as your water is in perfect equilibrium with the air (and depends on the CO2 levels in your air). Low pH can be a sign of poor aeration of your tank. Early on before I started skimming, I was able to raise my pH by adding a bubbler to my sump. If you don't have a good skimmer that really oxygenates the water, then you might consider something to improve aeration. In my nano, it was a HOB filter (with no filter media) that broke the surface of the water. Pointing one of your powerheads upwards to break the surface can help also.