Hi folks. Our pool construction was completed late in the season last year, so this is our first full season. We have had a couple algae episodes due inexperience and letting FC fall out of ideal range. We are concerned about damaging the vinyl liner by raising FC to shock level and beyond to mustard algae level if the need arises. Our liner warranty paperwork says maintain FC between 1 and 3, and I realize this probably does not account for CYA level. All that being said, does anyone know or have experience with what FC level would actually damage a vinyl liner?