There are several things you an do to correct that problem. I suspect you have a lot of Co2 in your home which is keeping your PH down a little. But, 8.0 is not bad and I would leave it at that. Check your PH when the lights have been on for a couple hours and check it when they have been off for a while. See what the lowest dip in PH really is and go from there. Also you can run a line outside for your skimmer air intake, that will more than likely correct your PH problem.
When adding ALK in your tank pay attention to what your adding. Soda Ash (sodium carbonate) will raise ALK and PH. The PH increase is temporary but it's a good boost, so add it slow and monitor PH while dosing or you'll wind up with hard sand.
The second ALK booster is Sodium Bicarbonate. That will raise Alklinity and have a subtle lowering affect on PH. Still monitor PH when dosing.
HTH both of you.
Happy Reefing
Jason