I have been a follower of the Pool Forum for several years now and appreciate all of the great information compiled here, thank you! I’ve usually been able to find answers to my questions/issues over the years by searching through the Forum. Somehow I cannot find my current problem addressed so I am posting for the first time – a newb.

I have a 24 ft. round AG pool with vinyl liner. I've had the pool for about 4 years now and noticed that over the past 2 years, it is developing a dark ring above the water line. We tried using some Soft Scrub but this was only very minimally effective. I’m a BBB’r so knew I might be risking water balance by using the Soft Scrub but fortunately it did not seem to have much negative affect on the 13,500 gallons of water. I have a couple of teenage daughters who like to have their friends over in the pool. They use tanning oil and my thought is that this ring is a result of their increased use of the pool and the tanning oil over the past few years. What is the best way to get rid of this ring and keep it away? Thanks for your help.