This tank sat in a shed for 2 years. I got it out, cleaned it, and set it up about 8 months ago. I didn't notice the hard water stains when I set it up, but it's been bothering me for quite a while now.
I've tried scrubbing it and scraping it it just won't come off. The water is crystal clear when you look in from the top but this line kills me.
Is this hard water stain?
Is there a way I can get this off without having to take the tank down?