An ugly ring at the waterline is normally caused by grease and oil from swimmers.
To resolve the issue you will need to clean the pool walls and surfaces regularly using tile and vinyl cleaner.
Also, keep in mind that overtime oil and grease can build up in your sand for you filter. Your filter sand needs to be changed every 5-8 years on average.
Didn't find the answer you were looking for? You can always contact us at firstname.lastname@example.org or choose the category below to see our most frequently asked questions for that topic: