I am putting a very long hose to connected to my skimmer valve and go straight to my small air vent in my bedroom 24hrs. I am also planning to put a big blanket to cover up my small refugium so the light is left on the whole night to control the PH swing. I really don't like the way it has changed too much from 8.3 down to 7.5 in the early morning.
Thanks for your inputs, guys. I hope I can find the solution to deal with this problem.

Be careful when covering your tank, you can actually increase the Co2 levels as the cover inhibits the exchange of gases.

Thanks for reminding me. I will try tonight and test it again tomorrow let see what happens. If it is not working I will just have to live with it as reefwars and everyone else has told me just to leave it alone.