As for the surface of the spa, wipe it down often. A little baking soda and a soft cloth will go miles for maintaining the surface of your spa, in ground or above ground, and it will help keep dirt and debris from floating around, getting into the filter and knocking your water out of balance.
With all that said, don’t hesitate to take out that spa filter and hose it down. Your spa system is going to work regularly to remove debris from the water, but regular water circulation and maintaining the balance in the spa is subject to passing mineral particles, calcification and other debris that can clog up filters. Think about a spa in the pines of New Hampshire – those needles fall endlessly. They wind up gathering in the filter, reducing the available surface area of the filer cartridge to do its job.
Pull it out, hose it off, put it back and enjoy a relaxing dip in the spa. It’s really that simple, and it’s one of the many things you can do to extend the life and enjoyment of your spa right now.