I've been getting small marks on bottom of pool that look like rust. I've tried the vitamin C in a sock on the spots but there is no change. I only hold it on for a few minutes. When I run my foot over them, they are smooth. Some of them are several years old. Each year I get a few new ones. We make sure everything is out of the pool each evening when covering it up. Our water is very clear so if anything fell in, I'd think we would see it or the cleaner would pick it up. Could something under the pool cause discoloration all the way thru? Pictures aren't the greatest. Used cell phone and held right at water level. I cropped them to try and focus in on marks. Any ideas?
These are along cove.
No sun when picture taken but you can see water is very clear.
These are along cove.
No sun when picture taken but you can see water is very clear.