need a different solution

I have a chlorine injection system pumping in to two 120gl retention tanks. From there I have a 2x9 blue GE filter canister that filters out the oxidized iron and other solid that may be inthe line. Due to my higher iron levels in the water I have to change this filter out ever 2 to 3 weeks because it gets plugged up with all the iron particals. Is there some other pre-filter I can use that will last longer. You can always tell when it's needs changing by the large pressure drop in the water output.

Thanks