There are several things that could cause you to still be getting staining:

1. It is critical that your system never run empty of salt.
2. It is important that the time of day be kept CORRECT and that no one uses WATER between 2 a.m. – 3 a.m. when the system is generating. While the system is in regeneration, any water used would be unconditioned (coming straight from the well).
3. It could be your resin TANK is too small to HANDLE all the iron.
4. It could be you are not regenerating often enough, or using enough salt per regeneration.
5. It could be that your iron content exceeds the recommended maximum. (1 cu.ft. of resin can effectively remove up to 3 parts per million iron with out additional treatment.)
6. On rare occasions the iron could be coming from just the hot water tank. If it is more than 20 years old it could be rusting out on the inside, thus putting iron BACK into the water. This is also true in older homes, again over 20 years old that used galvanized plumbing.

There are several things that could cause you to still be getting staining: