craig wrote:Hello WE tried the vitamin c tablet about 10 of them, my boys said it appeared to them to have no affect on these shadows, stains, I have to say since I really shock the pool and added ph plus they are getting a lot lighter, but also a few days ago I spread algae stop from hth all around the outside of pool and watered it well, we have marble stones all around the pool 2-5 inches in diameter just not sure what to think it still might be algae under liner but pool supplier said there was no way it would bleed through.but read on net that they could, if it is algae under liner would putting liquid clorax all around outside of pool kill the algae under liner.the liner is 3 years old from aqua-leader 20 mil. I like to add when I open the pool each year these spots are not there then as season goes on they appear. thanks for any help . sincerely Craig
Well, it definitely isnt metal then as the vitamin C tablets work instantly on metlal stains.
OK...step two is to place a chlorine puck on the stain and leave it there for awhile. If the stain lightens or goes away, it's an organic stain and you might have some luck with super-shocking the pool.