I have dug my pond, setup the protection underlay and installed my PVC liner,. And when we were trying to place the rocks we noticed that these kind of rocks will scratch the liner, I am waiting now to get other kinds of stones, this might take a week and the sun is so shiny these days, I am worried about the liner in direct sunlight, if i fill the pond temporarly with water will the underwater liner be protected from sunlight?

PS: i bought pvc liner because i couldnt find epdm liner in my country. I paid 180 USD for the liner (7x6 meters)