You will need to determine if your stains are organic or metals first.

Take a vitamin C tablet and hold it to the stain for a few minutes or if you have stain on the step or floor drop a tab on a spot that is stained. If in a little while your stain is lightened or removed the staining is metals. You will have to proceed with a metal stain treatment.

If you can hold a chlorine tablet to the stain and it lessens or removes it, then your stain is organic and you can raise your chlorine levels to remove the stains.