Asbury030,
If your PH dips to 7.8 at night and rises during the day then you should be ok since a good PH range is 7.8 - 8.3. The reason the PH will drip at night is because of the increase in CO2 throughout the over night hours. I agree with Bang that you should be careful getting your calcium too high so you might want to test for it before dosing it.
Here are a few things that could be casing you problems with your PH.
1. Due to CaCO3/CO2 Reactors
2. Due to High Indoor Carbon Dioxide Levels
3. Due to Low Alkalinity
For item number 3 try this test (I got this online):
Remove a cup of tank water and measure the PH. Then aerate it for an hour with an air stone using outside air. The pH should rise if the pH is unusually low for the measured alkalinity (if it does not rise, most likely one of the measurements (pH or alkalinity) is in error). Then repeat the same experiment on a new cup of water using inside air. If the pH rises there too, then the aquarium pH will rise with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise inside (or rises very little), then the inside air contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should).
I personally can not keep my Calcium over 350 so which is the reason I dose using my auto top off and my PH still drops to 7.9 - 8.0 at night.