In Cape Town west coast, where we only have course sand, surf wax works very well and extends line life. We just rub wax into the line, does not require melting.
Tried the same in NE Brazil, where sand is much finer, and found that sand sticks to the wax, same brand but warm water rating, and then acted like grinding paste - de-power line wore much quicker than normal.
So perhaps do a test run first and see how your local sand reacts
Yes I know plastic sleeve covered line will last longer, but I prefer the smother action of bare dyneema line