I had a new pool put in late last summer. We've been loving it. Over the winter I have kept the pool open and maintained it just like I do during the summer (all-be-it less chemical monitoring).
I have noticed a small rust-looking spot near one of the lights, on the wall (up and down, not where it rounds off to the bottom). It looks like a penny laid on the area and rusted and left a little streak ... but because its on the wall I know nothing simply fell there and stayed too long. I've been really good about getting out every couple weeks to continue brushing the pool. The cleaner still runs every week to clean anything off the bottom of the pool.
Here's the general location:
And here is a closer pic looking down at it (its located just about 3 ft down from the water line):
I have tried to scrub it off but it doesn't budge even a little. I can't exactly climb in and clean it by hand because a) I wouldn't know how to clean it and b) the water is so super cold right now (40+ degrees).
Any ideas of what it is or how one might go about cleaning it? Is this a possible defect that I should have the builder look in to?
Thank you much in advance.