I think if the tank wasn't already set up, drilled would be the best way to go, adding water volume, especially to a smaller tank is almost always a plus. Since the tank is already set up, I don't know if I'd go through the hassle of emptying it, etc and restarting the whole process, especially if it already has sand. If it's really new into the cycle (less than 3 weeks/hasn't spiked yet), I would be more inclined to think about dumping everything out and drilling the tank.