When it warms up a bit here, I am going to use the new Ryobi gas pressure washer to clean the aggregate driveway, patio and sidewalk. Does anyone have an opinion as to if using a concrete sealer afterwards does anything for the appearance or longevity of the concrete? Would this help keep the concrete cleaner so that I only have to pressure wash it every two years? If so, any thoughts on a good and easy to apply sealer? I have for decades been pressure washing concrete and never used a sealer, but now I wonder if I am missing something.