Becarful of putting in a calcite filter, as this will be the same as the iron birm filter. As soon as the clear water iron hits the calcite it will precipitate as the oxygen in the water and a pH >7.2 will cause oxidation of the iron to red ppt iron. if this is merely an upflow unit it will stop working in a matter of days.
You didnt mention any flow rates or size of the unit and how often you back wash.
One thing you also need to bear in mind is backwashing the unit, unless you have a clean water backwash, you will simply wash the unit with dirty iron containing water which will leave the filter dirty and then once the unit goes back into service it washes iron from teh filter into your pipes.
My recommendations - only use the calcite filter if you want to use an alternative ph adjuster, and use a backwashing unit which starts with a backwash daily then reduce as per demand. in order for iron to be removed you need a ph greater than 7.2. Please remember that using a calcite filter will increase the hardness of the water.
Fleck valves can be adapted to operate a clean water backwash - for your level of iron I would seriously consider this. For these levels of iron I typically oversize a unit - for example a 27ltr(1 cu ft) would be normal for a house - for very high iron levels I would use a 54lt (2 cu ft), dependent on the flows.
Clean your iron exchange resin with an iron cleaner - these are either salts with an 'acidic' component or a specific additive.
For more information you could also try posting
http://www.pentairwater.com/forum/