This was posted by PoolDoc in another thread this morning. It is concise and simple. A more thorough guide for dealing with metals in a pool is in the works, but for now, I'm going to copy below what he wrote and stick it at the top of this forum subsection.

Per PoolDoc:

Stain removal is a process, not a chemical.

And frankly it's not that easy.

First steps:

1. Maintain low pH (near 7.0) and low chlorine (<2 - 3 ppm) to avoid making stains worse.
2. Use polyquat to avoid algae while chlorine is low, and to help with filtration of small particles of metal salts that may form.
3. Test both your pool water AND your fill water accurately
4. If your fill water is likely the source of metals in your pool, do the bucket test on the fill water.
5. Tell us what sort of pool and gear you have.
6. Make sure your filtration is working properly.
7. Go through the process to remove metal stains from your pool surfaces and put them (the metals) back into the pool water.
8. Add a sequestrant to keep the metals in the water once you add chlorine back.
9. Use directed chlorination to try to collect metals (stains) on the dirt and particles IN the filter.
10. Clean the filter to remove collected metals.
11. Use CuLator to gradually, slowly remove metals that are still dissolved in the water

Relevant links:

Polyquat =>
Testkits =>
Bucket test for metals =>

That's enough for a start . . .