Pool stains

I have a new fiberglass pool and upon construction, several nails made their way into the pool and stained the bottom with rust. Any ideas on removal? Also, in you fiberglass pool owners opinion, what it the "acceptable and reasonable" allowance on how level my pool should be? My tile is off from 1/2 to 1 1/2 inches. Water levels don't lie.
I wish I had not chosen a tile that is 6 x 6 with the 1 inch squares. Should have chosen one with vertical only grout lines. Oh well!

"Iron Out", held captive in a damp wash cloth and then pressed against the stains, is your best bet.

As far as how much variation is acceptable . . . on commercial gutter pools, the answer is 1/16" of an inch. 1 1/2" is far, far beyond what I'd consider acceptable . . . but your contract will govern the dispute.

Thanks for the info. What is a "gutter pool"?

A commercial pool with some sort of 'trough' arrangement around the pool edge, instead of skimmers . . .