Worry about that bridge when it comes time to cross it. You're asking how to solve a problem that does't exist yet. The substrate in a SW
tank does provide some measure of buffering capacity, but you may not have a pH problem just because you're not using aragonite sand. Wait until the tank is setup, cycled and has been established for a couple of months. Monitor the pH, alkalinity and calcium levels in the tank and then decide if you need to take corrective measures and which supplements will work best for your setup.
While using the pickling lime/acetic acid solution will buffer the tank and raise calcium and magnesium, depending on the size of your tank it could also raise your pH to deadly levels. Try to become very informed before adding any chemical supplements to a tank.