Sounds like you have very high iron (so do I BTW). Water softeners will handle up to about 4ppm iron. Anything beyond that you will need an iron filter before the softener. However you need to provide us with a professional water test before anyone here can really recommending anything. These tests tell you how much iron, how much hardness, ph, etc. Someone in your area does water testing. Get a test kit from them, follow the instructions for obtaining a sample and return it to them. Make sure to bypass all filters, softeners, etc and let the water run for a few minutes before taking a sample.
Also what is the GPM yeild of your well and knowing what the cut in and cut out settings are on your pressure switch would also help.
Also what is the purpose of the 2500gal tank? A 2500gal holding tank isn't necessary to remove iron.