For me I use spit for my dome ports with super wide angle lenses. Water sheets but stays on the port, hence wet port. For flat ports and longer lenses I also used unscented candle wax and buff it with a microfiber cloth. However in the water need to maintain that dry port, so that's when I use the Shiseido face sunscreen. Also sometimes blow off those stray droplets from my flat port, but it can get hectic as waves roll through.I always used spit on my waterhousing ports, but can also apply unscented candle wax to the acrylic and buff it in using a clean, dry cloth.