David, have you tried using a mixture of water and that CLR cleaner? Might give that a whirl.

I had terrible stain problems with iron from my well and I have a white stucco home. Rust Aid is the only product I know that cleans the house and my white picket vinyl fence, too. Lowes carries this product.

a solution of ordinary household bleach & water may prove effective start at maybe a 50/50 mix & adjust according to results. also you might try (rid- o-rust) a solution used in underground sprinkler systems to prevent rust stains charles w.

I have had success with Bar-Keepers Friend, available in super-markets cleaning section. I believe the effective ingredient is oxalic acid, also sold as wood bleach in hardware stores.