Turf needs to be secured with nails to hold it down and the nails are non galvanized because it’s the rust that actually secures the turf down in time. Sand is always needed if you want your turf to last and take traffic. The higher the number (60 grit for example) the more fine and heavy the sand is and should only be used to sink into the fine holes of a putting green turf. The lower the number (16 grit) the more the silica sand gets in between the blades of the turf to keep them standing up and looking uniform, creating gaps between the blades for drainage and making sure the blades don’t move around and get worn over time. The more sand you put the better but don’t go over the recommended amount on the product spec card. Zeolite silica not only reduces pet odors but can reduce heat because it locks in moisture.