Would appreciate professional advice! Have just laid down floor in porch and utility room using reclaimed 9"x9" quarry tiles. Should we clean and seal tiles before grouting? If so, which products would you recommend? Have seen numerous products online e.g. Lithofin, Aquamix, Fila etc but am now rather confused! The tiles are in a good condition ( were previously on a kitchen floor) but do need a clean. I would like a durable finish to keep maintenance to a minimum! A friend suggested we clean them first with a coarse cleaning fleece on a grinder. Would you recommend this as a first step?