Our deck is grey and weathered and a new one is a few years away. In the meantime, we thought we’d clean and re-stain it. We powerwashed it – though afterwards we read that maybe we shouldn’t have, if it’s pressure treated, and that we shouldn’t sand the deck for the same reason. The problem is, we don’t know if it’s pressure treated. The inspector, when we bought the house, said it isn’t, but consequent contractors said that it is. I know pressure treated wood has the greenish tint but I don’t know if any tint on the wood now is because of residual mildew or not? In any case, the wood, though now a bit cleaner, still has a lot of deep grooves. Can we sand it down a bit and then restain? Should we be concerned that the wood might be pressure treated?