Rust-colored water and stains on your pool tile or liner can be unsightly, and it can require determination to eradicate the rust. Very high water acidity can corrode the metal pipes and fittings within your pool's circulation system. Those damaged particles are oxidized by the chlorine shock doses you normally give your pool water to keep it clean, causing more rust to form. Once the problem has been diagnosed, you must regularly monitor the pH levels in your pool water and replace any damaged pipes that may be causing this problem.
Test the pH level of your pool water to determine if it's within the normal range.
Drain your pool completely. Wait a day or two for all the water to drain out.
Locate your pool's various pipes. Replace any metal or iron-containing pipes with PVC or copper pipes or fittings. These materials will not rust and are very durable over time.
Clean the rust stains that may have formed on the tile and/or liner of the pool. Scrub the surfaces with a scrub brush and a high-grade pool cleaner that is safe for liners and tile.
Refill the pool with water. Add the correct chemicals to your pool system to keep the water clean and the pH level normal.